hp elitebook 8460p powering problem

Hello,

A customer brought this hp elitebook 8460p when not powering or charging.
I disassembled cleaned it, after that i inserted the chager, the charging led lights up then fan spins for a while then goes off,
it seems like a short but am unable to locate exactly.
I have also realised the web switch also acts as power on switch. I have tried looking for faulty fets and capacitor in no vain.

Please am here seeking your help.