Psp keeps shutting down?

i have a psp 1000 model, and recently a problem started with it. when i do not have a UMD in the drive, it will start fine. as soon as i put a UMD into the drive and close it, the psp shuts down. it will also immediately shut down whenever the WLAN switch is turned on. i have reset to factory defaults, formatted the memory stick, and did a hard reset to try to fix this, to no avail. can anyone help? and please, no answers saying its bricked. if it was bricked, it wouldn't turn on in the first place