After reading all of your posts about this issue, my conclusion is that the IR is broken on your v2 in some way.
Could be a burnt out bulb?
I have a v2 with the exact same problem. I got it used aswell (mine was from ValueVillage for $1 with a bunch of other Tamagotchis, so at least we didn't pay much XD).
:/
It's the risk you take when you buy used, unfortunately.