Incognito computer technician

A laptop's fan has become noisy. We decide to open it and fix it. 2 hours later, the computer is open. 1.5 hours more and it's closed again. Computer boots up and it's amazingly silent. I love it when a plan comes together :-) Fire up some demanding apps and it's still silent... no signs of the fan... Oh wait... Did you plug it back in? I didn't, and you? Oh... (both) sh1t!!!
For the record, the 2nd time it took 45 mins to disassemble, plug the fan in and assemble. At least, after the whole even working, the effin fan was fixed.