So I have a coupe and my stereo was directly wired to the battery through a wire with a fuse I decided to clean my battery as it had lots of corrosion and that said wire was brittle enough to snap off or something and that’s when my stereo stopped working yesterday, today I just press my back window button too see if it was still broken but suddenly it moved up and down so my question is if there isn’t enough power somehow to have my stereo on and one back window working at the same time or is it something else and it fixed itself?
Weak batteries can do some strange things. A lot of times if you see corrosion on the battery posts it’s a sign your battery is towards the end of its life. You can bring it to a parts store for a free inspection.