The national Sabbath keeping obligation on the sons of Israel under this
contract was (verse 2):
The penalty for breaching this was (verses 34,35):
This penalty is saying that the number of years of exile will equal the number of missed Land Sabbath years. Now we know from various scriptures, in addition to Ezekiel 4 and the calculations of section  that this exile was 70 years long.
19 And he proceeded to burn the house of the [true] God and pull down the wall of Jerusalem; and all its dwelling towers they burned with fire and also all its desirable articles, so as to cause ruin.
What Jeremiah said was:
The word that occurred to Jeremiah concerning all the people of Judah in the 4th
year of Jehoiakim the son of Josiah, the king of Judah, that is, the first year
of Nebuchadrezzar [aka Nebuchanezzar]
the king of Babylon [604 BC].
2 which Jeremiah the prophet spoke concerning all the people of Judah and concerning all the inhabitants of Jerusalem, saying:
3 From the 13th year of Josiah the son of Amon, the king of Judah, and down to this day, these 23 years [from 626 BC to 604 BC] the word of Jehovah has occurred to me, and I kept speaking to you people, rising up early and speaking, but you did not listen (Jeremiah 25).
Therefore this is what Jehovah of armies has said, 'For the reason that you did
not obey my words,
9 here I am sending and I will take all the families of the north [the Northern Kingdom of Israel was already under the authority of Nebuchadnezzar since the fall of Nineveh, the Assyrian capital to the Babylonians in 612 and then the fall of Harran, their secondary captial, to Nabopolassar in 609 - Cambridge Ancient History - Wikipedia. For the Assyrians ruled Samaria until they were defeated by the Babylonians. But the Babylonians implemented exile programs], is the utterance of Jehovah, even [sending] to Nebuchadrezzar the king of Babylon, my servant, and I will bring them against this land and against its inhabitants and against all these nations round about; and I will devote them to destruction and make them an object of astonishment and something to whistle at and places devastated to time indefinite.
10 And I will destroy out of them the sound of exultation and the sound of rejoicing, the voice of the bridegroom and the voice of the bride, the sound of the hand mill and the light of the lamp.
11 And all this land must become a devastated place, an object of astonishment, and these nations [the ones round about and the Northern Kingdom of Israel, but not Judah or Jerusalem] will have to serve the king of Babylon 70 years.'
12 'And it must occur that when 70 years have been fulfilled I shall call to account against the king of Babylon and against that nation,' is the utterance of Jehovah, 'their error, even against the land of the Chaldeans [Cyrus took Babylon in 539Tishri BC], and I will make it desolate wastes to time indefinite (Jeremiah 25)
So the period of 70 years of Servitude for the Northern Kingdom and the nations round about ended in 539Tishri, when babylon fell to Cyrus, and so began in 609Tishri. 609Tishri was the end of the last land sabbath which was missed only by the northern kingdom - see .
The situation was different for Judah...
12 So the angel of Jehovah answered and said: O Jehovah of armies how long will you yourself not show mercy to Jerusalem and to the cities of Judah, whom you have denounced these 70 years? (Zechariah 1).
The 70 years period of servitude for the North was a 70 year period of denounciation for the south, for Judah and Jerusalem. Now Jerusalem was destroyed and the temple was burnt by Nebuchanezzar on 586Ab10
12 And in the 5th month, on the 10th day of the month, that is,
[in] the 19th year of King Nebuchadrezzar, the king of
Babylon, Nebuzaradan the chief of the bodyguard, who was standing before the king of Babylon, came into Jerusalem [586Ab10].
13 And he proceeded to burn the house of Jehovah and the house of the king and all the houses of Jerusalem; and every great house he burned with fire.
14 And all the walls of Jerusalem, round about, all the military forces of the Chaldeans that were with the chief of the bodyguard pulled down.
15 And some of the lowly ones of the people and the rest of the people that were left remaining in the city and the deserters that had fallen away to the king of Babylon and the rest of the master workmen Nebuzaradan the chief of the bodyguard took into exile (Jeremiah 52).
21 ...Thus Judah went into exile from off its soil (Jeremiah 52).
The situation was different again for Jerusalem which went into exile twice!
At length Jehoiachin the king of Judah went out to the king of Babylon, he with
his mother and his servants and his princes and his court officials; and the
king of Babylon got to take him in the 8th year of his [Nebuchadnezzar's,
13 Then he brought out from there all the treasures of the house of Jehovah and the treasures of the king's house, and went on to cut to pieces all the gold utensils that Solomon the king of Israel had made in the temple of Jehovah, just as Jehovah had spoken.
14 And he took into exile all Jerusalem and all the princes and all the valiant, mighty men, 10,000 he was taking into exile and also every craftsman and builder of bulwarks. No one had been left behind except the lowly class of the people of the land.
15 Thus he took Jehoiachin into exile to Babylon; and the king's mother and the king's wives and his court officials and the foremost men of the land he led away as exiled people from Jerusalem to Babylon (2 Kings 24).
The words of Jeremiah the son of Hilkiah, one of the priests that were in
Anathoth in the land of Benjamin;
2 to whom the word of Jehovah occurred in the days of Josiah the son of Amon, the king of Judah, in the 13th year of his reigning [626 BC].
3 And it kept on occurring in the days of Jehoiakim the son of Josiah, the king of Judah, until the completion of the 11th year of Zedekiah the son of Josiah, the king of Judah, until Jerusalem went into exile in the 5th month [586Ab] (Jeremiah 1).
So Jerusalem went into exile in 597 when the court of Jehoiachin was removed and then again in 586Ab when the court of Zedekiah was removed. Whereas Judah did not go into exile until the 19th year of Nebuchadnezzar, which was 586, in particular on 586Ab10. But Jeremiah had been speaking God's word to them since the 13th year of Josiah, which was 626. So presumably he started denouncing them in 609, when the Northern Kingdom started serving the King of Babylon. So Judah got 23 years of denunciation followed by 47 years of exile and servitude, whereas the Northern kingdom and the kingdoms around about got 70 years of servitude. Jerusalem got 12 years of denunciation followed by 58 years of exile. The land exiles of Jerusalem and of Judah ended with the decree of Cyrus in his first year of 538...
And in the first year of Cyrus the king of Persia, that Jehovah's word from the
mouth of Jeremiah might be accomplished, Jehovah roused the spirit of Cyrus the
king of Persia so that he caused a cry to pass through all his realm, and also
in writing, saying:
2 This is what Cyrus the king of Persia has said, 'All the kingdoms of the earth Jehovah the God of the heavens has given me, and he himself has commissioned me to build him a house in Jerusalem, which is in Judah.
3 Whoever there is among you of all his people, may his God prove to be with him. So let him go up to Jerusalem, which is in Judah, and rebuild the house of Jehovah the God of Israel he is the [true] God which was in Jerusalem.
4 As for anyone that is left from all the places where he is residing as an alien, let the men of his place assist him with silver and with gold and with goods and with domestic animals along with the voluntary offering for the house of the [true] God, which was in Jerusalem (Ezra 1).
But there is another interesting exile which befell Jerusalem and Judah. They had 70 years without a temple. The temple was burned in 586 Ab. The temple which Cyrus claimed he was commissioned to build was inaugurated before the passover of 515Nisan (in 516Veadar). Of course he wasn't, because no Persian was ever commissioned by God to build a Jewish temple. Cyrus didn't finish it anyway, and Zerubbabel did. So Zerubbabel was the one who was really commissioned by God to build the second temple in Jerusalem:
And they completed the house by the 3rd day of the
lunar month Adar, that is in the 6th year of Darius the king.
16 And the sons of Israel, the priests and the Levites and the rest of the former exiles held the inauguration of the house of God with joy…
17 And the former exiles proceeded to hold the Passover on the 14th of the first month (Ezra 6).
The 6th year of Darius Hystapes was 516N to 515N (CAH). Notice how everyone is now defined as 'former exiles'. Between 586Ab and 515Nisan there are 70 agricultural years from 586Tishri until 516Tishri. But this is a temple sabbath, a sabbath, a release from temple duties which is also a release from the law of Moses, which cannot be followed without a temple (something which modern physical Jews deliberately ignore, in a vain attempt to justify their rejection of the one through whom they were all made - Jesus Christ - Michael - the guardian angel of Israel, for all the thanks he got). So it is measured in sacred years from Nisan to Nisan. So the 70 year sabbath would run from 585Nisan to 515Nisan. The year 515 had a temple at the beginning of the year because it was finished in Adar of the previous year. Incidentally 516Adar3 was 8th February, and 515Nisan14 was 14th April, so there was a second Adar in 516, see - BLC. Now it must have been the case that the temple was 'inaugurated' (without the Law of Moses which was re-entered in 455Tishri by an oath) before 515Nisan1, so that the year 515 was not a temple sabbath year. This is why we are told that it was finished on 8th February 515 (516Adar3 - 516 in Hebrew years and 515 in Gregorian years). In fact it may well have been 'inaugurated' on Veadar14, this would nicely symbolise the fact that it was inaugurated without law. and would therefore need another inauguration.
As regards the temple exile we read...
In the first year of Darius the son of Ahasuerus of the seed
of the Medes, who had been made king over the kingdom of the Chaldeans;
2 In the first year of his reigning I myself, Daniel, discerned by the books the number of the years concerning which the word of Jehovah had occurred to Jeremiah the prophet, for fulfilling the devastations of Jerusalem, [namely,] seventy years. (Daniel 9).
This is the 'Devastation of Daniel 9' rather than the 'Denunciation of Zechariah 1'. The devastation applies to Jerusalem, and therefore to the temple there. The first year of Darius (Hystapes) the Mede was 521, so the 70 years that Daniel refers to was still going then. So it must have started after 591 BC.
Furthermore, it came about that in the
4th year of Darius
the king the word of Jehovah occurred to Zechariah, on the 4th [day] of the
9th month, [that is,] in Chislev...
5 "Say to all the people of the land and to the priests, 'When you fasted and there was a wailing in the 5th [month] and in the 7th [month], and this for 70 years, did you really fast to me, even me? (Zechariah 7).
This is Darius Hystapes whose first regnal year was 521Nisan to 520 Nisan (Cambridge Ancient History). So fasting and wailing was occurring in the year from 518Nisan to 517Nisan. So the 70 years of exile on the priests of Jerusalem was still going in 518/517.
As regards the 70 year exile of ‘the families of the North’ this was the Land Sabbath repayment, since it started in 609Tishri at the end of the last missed land sabbath in the Northern Kingdom (Judah did not miss this sabbath). The 70 year exile from the Temple, was the Southern Kingdom’s exile, this was not a land sabbath exile, since if one could return to the Northern Kingdom in 539Tishri, then one could certainly also return to the Southern Kingdom at that time. It was actually an exile from the Temple, ending with the inauguration of Zerubabbel’s temple in 516Adar. So it was also an exile from the law, since one cannot obey the law without access to the temple (Modern Jews please note!) So it was a 70 year Sabbath from the law of Moses. To summarise:
70 year exile for Israel and kingdoms round about: 609Tishri (last missed
sabbath in North) - 539Tishri
(Cyrus takes Bablyon)
70 year denunciation for Judah: 609Tishri (last missed land sabbath in North) - 539Tishri (Cyrus takes Bablyon)
70 year temple exile for Judah: 585Nisan (first sacred year with no temple) - 515Nisan (start of first sacred year with temple).
Incidentally, temples are normally inaugurated either in Nisan at the Passover or in Tishri at Booths. Zerubbabel's wasn't in 516Veadar because the Jews weren't under law at the time. Zerubbabel's temple was inaugurated again in 455Tishri, the month in which the Jews agreed to go under law again - see U98.