Recovery to 1.50 Using these recovery files:
Direct 3.40OE-A Recovery
Then U can update back to 3.40OE-A.
I would suggest U update to a newer firmware like 3.52M33-4 or 3.71M33-4.
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=Direct 3.40OE-A Recovery=
=====================Download this rar: http://www.mediafire.com/?bzj9ldcuzow extract it.
Power off your PSP by holding the power button for 10 sec.
Then HOLD the "R" trigger and turn the PSP on.
When the Recovery Mode turns on:
Press "X" Toggle USB -ON- Copy the RECOVERY folder to the GAME folder.
Press "X" Toggle USB -Off-
(Plug in your AC Charger battery needs to be at 75% or more.)
U CAN also just press X on the Run program at /PSP/GAME/RECOVERY/EBOOT.PBP then right away HOLD "L" Trigger and Triangle button and it will bypass the 75%
battery Check.
Run program at /PSP/GAME/RECOVERY/EBOOT.PBP and press "X"
It will ask U to agree and press "X"
DONE!
====================
=3.52M33-4 for 1.50 PSP=
====================First U will need to run the kxploitpatcher since your on 1.50.
Download this rar: http://www.mediafire.com/?eth0meht0hmCopy kxploitpatcher and kxploitpatcher% folders from "1.50only/" of this download to your "ms0:/PSP/GAME/" and use it.
Then just use this:
3.52M33 & M33-4 Update:
Copy the M33UPDATE_352 to ms0:/PSP/GAME and Copy the M33Update4 to ms0:/PSP/GAME150 folder and launch the 3.52M33 installer.
(Plug in your AC Charger battery needs to be at 75% or more.)
(U CAN also Just HOLD "L" Triggre and Triangle button and press X on the 3.52M33 installer and it will bypass the 75% battery Check.)
Then U need to go into Recovery Mode:
Power off your PSP by holding the power button for 5 seconds.
Then HOLD the "R" trigger and turn the PSP on.
When the Recovery Mode turns on:
Go into Configuration:
Set your Game folder kernel to 1.50 (It will be 3.52)
Press "X" on back
Press "X" on Exit
Then use the M33-4 Update.
DONE!