I've read dozens of posts from people complaining of similar problems, but nothing exactly the same as this.
I have a silver slim, the Daxter one, I think(got it used.) I'm running CFW 5.00 M33-4, and the battery found at dealextreme.com/details.dx/sku.15153 The battery is new, and I haven't had any trouble with it at all.
Okay, here we go. The PSP was working perfectly a couple of weeks ago. It ran from the AC, and from the battery. It charged perfectly fine as well. But for the last few weeks, I've been busy and haven't used it at all. So now I go to play Dissidia, which I'd been dying to play, and it won't turn on. Plugging in the AC adapter, it works fine, and charges the battery. But with just the battery in, it does nothing. Hit the power switch, and you get no lights at all, nothing on the screen, no response whatsoever. If I turn it on with the AC plugged in, and then pull the plug, it'll stay on for a second or two before losing power, instead of shutting off instantly, like if the battery weren't in.
I know that battery is fine, because not only does the built in power tester show that it is full, but I tested it with my multimeter and it shows a nice full charge. I've tried leaving the battery out and system unplugged overnight, but that did nothing. I've tried putting the battery in while the PSP is already turned on with the adapter. I've tried countless other things that I thought might help, but all turned out to be pointless. I've also tried putting the battery into Pandora mode and booting into that, but that gets no response out of the PSP either. Worked fine to downgrade, not more than 2 months ago when I got the thing.
Has anyone dealt with this problem before, or have any idea what might cause it? In those 2 weeks that it wasn't in use, it was safely stored away in a soft carry case in my desk, so I know that it didn't meet with any unfortunate accidents. I just don't get it. Any help at all is appreciated.
Also, The same day I used the battery to install CFW on the slim, I also used it to install CFW on a PSP phat that I had. I'm told that putting a slim battery into a psp phat will ruin the battery, but I used it after that with no trouble until now.