If you don't have either of those games, you could use this 2.80 downgrader that doesn't require it. Even though it was made in January, it has all the latest fixes built in. Of course, it does require you to update your PSP from 2.71 to 2.80 (NOT 2.81, 2.82 or higher!).

Once you've downgraded safely, you could upgrade to the custom firmware 3.51 M33, of which version 7 is now available, with more TA-082 fixes built in.

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