Bought Marvel Nemesis and the UMD ask to uograde to V1.52 to be able to play the game. Silly me I upgraded. Now I want to downgrade to back to Ver1.50. But in order for me to downgrade, I first need the version 2.0 up grade as per other references.

try psp updates.com and try the 2.0 eboot loader

rent socom fireteam bravo... it will ask u to update to version 2.0 before you can play the game...