Only thing you can do is buy a flasher and downgrade to 3.55 or lower. If your system was never on 3.55 or lower to begin with, than you can not downgrade to 3.55 or lower. Once you hardware flash your system to a hackable firmware you can play all 3.55 (2011ish) or older game backups. To play newer backups you must convert your console to a DEX (developer) console and then manually repackage the game backups with the leaked Sony developer tools.
So to recap. You need to buy a flasher like the Progskeet or E3 Flasher, then flash to a lower firmware, hack your console, and optionally update to higher level DEX firmwares. Converting to DEX is kinda challenging, but allows you to play 3.55 or older games, the latest retail games, and most 3.56+ backups. Good luck! This is why I never left 3.55. Patience pays off.