iFixit

Firmly stuck to the battery is a trilingual Warranty Void seal. They really covered all bases with this one, as long as you know English, French, or Spanish.

Good news: the battery is not soldered to the board.

Bad news: unfortunately, you have to peel the warranty sticker back to remove the battery.

But more good news: if you're careful, you can remove the battery without disturbing the "VOID" portion of the seal, but we didn't tell you that.

Just slide a PSP opening tool in between the battery and sticker. Work your way gently side-to-side, until the battery is free from the sticker. Presto-changeo!