G'day Doc, open the lappy up and make sure all of the internal connectors are seated properly.

Remember, it worked and you have made internal changes.

Start there and work outwards before blaming stuff that works properly on the other machine.

Could well be a compatibility issue but given it has had surgery that must be the first place to look.

Remember despite keeping strict item counts surgeons still leave bits of kit and swabs inside patients occasionally.

It is human to err