I skimmed the posts, but couldn’t quite locate if the issue persists if you leave the printer alone for a few hours/days and then come back to it later. (As in would it be able to complete a print before exhibiting this issue again) Seeing how it worked fine before and doesn’t anymore, especially if in a consistent matter, irregardless of settings, might be a chance you blew a capacitor and it’s trying its best to cope with that situation. Unfortunately without replacing the board with a confirmed working one it’s hard to tell if that’s the case… plus depending on the level of damage it might appear as intermittent problems that sometimes manifest without rhyme or reason on 2 potentially identical prints.

Looks fantastic. I recommend also printing a cover for the UPS sockets with removable covers for the plugs you wish to use as it looks like you have quite a bit of dust circulating there