O.o? did you fix it? Are you sure all the pins line up? like
1234
1234
not
1234
-1234

 Also on the other side if that I think there are a bunch of bronze bars leading into the nubby (The correct name for your so called joystick) check if any of those are bridged with some dust or some metal, if they are remove it or blow the dust off.

Also clean the inside of the front face plate and the lcd itself. You probably haven't noticed this but it's probably pretty dusty. Sadly, you will never get all the dust out after you remove the face of the psp.