I have run into an issue with my GBA. I just modded it with the M2 kit and most of the time it doesn't turn on. I have to turn it on and off multiple times before it decides to stay on. When I turn it on you can see the light turning on but then when the switch gets to the end of the "movement" it's off. I think when the shell is not screwed in and there's some space between the front shell and the back shell the issue is less pronounced.
But I found a similar issue with my non-moded GBA SP, in that once it's on if you slightly touch the on/off switch (without actually turning it off) it turns off.
I already cleaned the switch with alcohol when I harvested the board.

Does anyone have any idea how to fix this?