I did not find the good category for this, might be better in older consoles but well…
I did buy this GBA SP 2days ago and after like 10mins of playing with it I did notice the light going red sometimes. At first I thought the battery was about to die since I did not charge it yet. But then I fully charged it (it did charge with orange light when plugged) and I kept playing my pokemon game and suddenly the light was flashing without any logic pattern. Then it did shut down.
I have tried to replace the battery but did not affect the issue. I also added a shim under the battery to see if it had anything to do with a potential lack of tightness. Nothing changed.
I will be opening it soon but I wanted to know if anyone ever dealed with a similar problem.
I have a video to show the problem but I cannot link it here