hehe no not 50% something like 68%

' if you pull out the power cord and battery exactly at 68% it will have just copied all the neccesary (1.5) firmwares, and if you restart ur psp you WILL have 1.5 and you can just update to any custom fw you like! but if you're too late and ts 69% or above, you will brick or if you don't pull ou the power u will have 3.30 so ull have to wait even longer for another chance to downgrade..

just do it, it really works this is how i downgraded and im happily using 3.03OE now :)