well, if you'd like, you can keep up with the oe-updates: the newest is 3.40. this will also lead him to play other games like snes, nes, etc. and homebrew.
if you really want to downgrade, go in usb mode, and add a folder to the root, "RECOVERY", like that. in this folder, i'm not sure exactly what you put in it (but hopefully one of these good people do know). then hold the power button in until it shuts off, then restart it holding the R button. go to the selection that says "run RECOVERY folder", or something like that. then after you're back at 1.5, go to the system update, or download the newest from playstation's website.

hope that helped (a little)

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