please help me help a friend

hello all
My friend has upgraded his psp to 3.40 oe-a.It all was ok and but now it not a well psp. If you have a memory stick in the thing will not start and the red light flashes then stops then flashes then stops and on and on. It starts up fine without the memorystick in. I have tried my memorystick in his machine and it does the samething and when i tried his memorystick in my psp it was fine please could you tell me how to solve this problem as i havent got a clue

as a 1st step , check that all recovery mode settings on the 2 consoles are identical .
i get this same thng if i enable autorun with no psp/game/boot folder on ms0.
while the drive light flashes you should still be able to access recovery with R .

This has happened to me actually, either delete a file that u rectely put on it or reformat the memstick bit of a pain though lol

thank you for the advice.i formated and i am back on track