原帖由： originalmachead ,
On board dc-in circuit, faulty power button/damaged top case. If someone has been in it before you they may not have completely or correctly reassembled it. It will take a lot of troubleshooting, examination to determine where the first or major problem lies. If the battery is charging that could eliminate the DC-in board as suspect. ''If this Answer is helpful '''please remember to return and mark it '''Accepted.''