For my brother's birthday, I bought him a $20 Playstation card, with which he bought Final Fantasy VII and another game. (Can't remember what exactly; I don't think it's very relevant, however.) We left the PSP plugged-in overnight to download Final Fantasy VII, but when we checked it the next morning, the PSP had apparently died. It won't turn on; the charging light won't come on; and buying a new battery didn't help. (I don't know why I expected it to.)
As I just mentioned, we bought a new battery for the PSP, a Sony-brand 2200 mAh high-capacity battery, as we guessed it would help. We put in the new battery, plugged it in, and tried turning it on; the PSP wouldn't work: however, we didn't give it time to charge, however relevant that might be (but he decided to give up because the charge-light didn't come on anyway).
Any ideas as to what's wrong on a concrete level and how to remedy the problem would be greatly appreciated.
Okay, I figured out that there was no problem with the PSP itself; it was the charger. I tested it by having my friend bring his charger over; it works! He's letting me borrow his USB charger while he keeps his wall charger.