So I have been using my 88 Pro quite frequently for music production and playing games with MIDI support, but I left it alone yesterday since I had nothing to do on it. Before this I had powered it on basically twice a day to use it. I went to power it on today, and it doesn't start up anymore. It lets out a little pop from the analog outputs when powered off like normal, but the screen stays dimmed and there's no audio while it's supposedly powered on. No combination of buttons when starting the unit up does anything. It's done this before, and I managed to solve it by removing the battery and replacing it, but this time I removed the battery and it's still totally dead. Left it off for about 15 minutes, plugged it back in without any battery, and it's still dead.
I've tried running it without the battery in the past, which I thought would solve it, but it did this anyways. It just seems to happen when it's left off for a long time, and this time it won't come back. Any advice?

Board pics:
https://i.imgur.com/4XoSLj6.jpg
https://i.imgur.com/1QDiyHh.jpg
https://i.imgur.com/6fjSz3F.jpg

EDIT: Aaand it's magically fixed again. I unscrewed the whole thing, got some dust off of the analog board, screwed it all back together, and it's back to working. 😕