Just to share my experience with the restoration of one A2 rev3 and one europlus.
Both have bad keyboard logic. Recently i managed to buy 2 keyboard encoder chips (MM5740AAE) from online store www.littlediode.com ( UK based ) . The Apple 2´s keyboard worked 100%. But the europlus did not. I´m suspecting that something must be wrong with the logic board besides the encoder chip.
From the 2 keyboard encoder chips that i got, 1 is ok and the other is defective. I´m currently waiting for a reply from littlediode for a replacement request.
I have an Apple 2e board without keyboard that upon power up displays those squares and beeps from time to time. I understand that it is normal because the board has no keyboard connected. Is there a way to force the keyboard detection so it can boot up ?