Gaia Manager and mutiman not recognising hdd

i have just downgraded my friends phat ps3 from 3.5 to 3.41 i then installed gaia manager and mutiman, when i plug in my external fat 32 hdd which has the ps3 games in a GAMEZ folder no games show up. i then downgraded the ps3 to 3.21 then back up to 3.41 and installed both gaia manager and multiman again but i get the same problem i click on gaia manager and just get a black screen.
the only thing i can think of is that he said his bluray broke a while ago and he put another one in with another logic board could this be the problem due to wrong logic board?
on my own ps3 the hdd shows up fine, any ideas thanks