I always wonder wether an incorrectly configured ubuntu kernel or drivers could actually damage modern computers. I remember viruses from the 80's that supposedly could kill the machine by asking the bios to increase and decrease voltages or hdd spin in such a way it would deal physical damages to the machine. Might have been a computer legend though.

Note: When returning laptop, desktop, smartphone or anything I always tend to be anal retentive and put everything back in place, including software and OS so there are no arguing wether the problem is software or hardware (obviously I only need to send back hardware defective devices).