Guarantor Of Redemption

א"ר ברכיה מ"ד והארץ היתה תהו ובהו
Sefer HaBahir, verse 2, line 1 excerpt

"Rabbi Berachiah said: it is written, 'the earth was chaos and desolation' ..."

The hebrew word היתה is translated "was" in this excerpt. Why does the quoted phrase from Bereshit 1:2 use the word היתה - and not use either the word היה, or the word ויהי, both of which also mean [1] "was"?

A clue ...

היתה has a gematria of 420, which reduces to 4 + 2 + 0 = 6 = ו (vav)

in contradistinction to היה which reduces to 2,
or to ויהי which reduces to 4

As written in a previous entry, Reconciliation Of Darkness & Light, היתה is from the root יתא which implies "forward projection". And what is being forwardly projected here by the use of this "was" form?

Answer: the shared ו of אליהו and of יעקוב; where the letter ו is the guarantor of redemption [1]

Footnote:

[1] R' Michael Munk, The Wisdom In The Hebrew Alphabet, on the letter vav, pages 97 and 95