Slow Gameboy Advance SP

I found an old GBA SP that I owned about 10 years ago and remembered that the SP just suddenly stopped working mid game and just displayed a white screen. Afterwards, the GB would just boot too a white screen - no sound, no GB logo, no “Ding”.

I am currently in the hobby of repairing these units as well as the DMG-01 and the GBP, but I cannot for the life of me figure out what happened back then.

I finally opened the console a few days ago and or original there seems to be no corrosion on the board. No leaks, even the water indicator was not triggered. Screen light still turns on.

Yesterday I powered on the SP upside down and gave it a few taps and it booted, but was running slow. The sound as well was slow. The SP read my games fine, but it also played games super slow.