you need to learn how to troubleshoot.
1st of all, let me explain why that happen.
i have repaired around 2 psp that have this problem.
this problem occurs when the mobo detect there is an UMD in the UMD driver.
this video shows 1 of the PSP that i have repaired.
MOV04302.MPG as you can see it wont load XMB menu.
here i demonstrate on a normal working PSP how that problem occurs.
MOV04310.MPGi tape the UMD switch just to trick the mobo in thinking there was an UMD in it.
so the 1st thing you need to do is desolder the switch. check if the switch are broken.
after you have desolder the switch, turn on the psp and check if the xmb are working fine again.
but if the XMB are still not loading.
you have to rework the UMD BGA
here is a video showing how to rework a BGA
BGA reworking without special reballing equippmentthe result after reworking the BGA?
MOV04305.MPGtry to get a template like this to make your job easier
you can see most of my work here/
http://wetfusion.blogspot.com/2010/03/modders-days-out.html