Power indicator randomly changes, sudden restarts of game

Hi,

I dug out my old GBA SP a little while ago. As it was unable to hold a charge for much time at all, I replaced the old battery that also had swelled a bit.

Now, it charges and holds the charge like it’s supposed to but I’m having an issue where the power indicator randomly turns red and then back to green when playing. There are also cases of the game suddenly restarting (making me lose a bunch of progress in a game) though this is more infrequent.

I’m guessing that this is due to some sudden dips in current from some glitchy connector somewhere, possibly due to the previous battery having been swollen and putting pressure on it.

My question is if this is something other people have experienced or if anyone knows how I would go about finding and fixing the issue… Where should I start looking and what am I looking for?

I unfortunately do not have access to a multimeter or a soldering iron (I haven’t soldered anything since high school and even back then, I was really bad at it).

So, how do you guys suggest I start going about this?