>>717950337 (OP)
On an old model like that?
Hope and pray.
Otherwise, hand it in to a guy who can do BGA swaps so he can frankenstein a more reliable GPU into it. You're better off selling it if it still works, and getting a PS3 Slim (that can be CFW'd) and a PS2 Phat (so you can mod it with FreeHDBoot and have an OPL library).
While being able to play PS1, PS2, PS3, PSP, and whatever homebrew comes with those platforms all on one console is really neat, it's way too unreliable these days to be a serious option.