My parents' Mac Mini 2011 suddenly switched off yesterday, then today it switched off again and they were unable to turn it on. No light, no power, like it's not even plugged in. I initially tried to turn it on with no success, so I opened the chasis and did some major scrubbing to get rid of all the dust. Plugged it back in and now it turns on just fine. One thing is that I never liked how hot it got, and it was stashed in a cupboard space with no ventilation, so I'm thinking maybe it was a combination of dust buildup and lack of ventilation that eventually caused it to suddenly turn off like that. To resolve it, I moved the Mini to an open desk with PLENTY of ventilation and space to dissipate heat. Now after a few hours of use, it is mild to the touch whereas before it used to run pretty hot. Could that have been all it was? I thought it might have been the power supply or logic board failing because it wouldn't even turn on, but maybe not if this holds. I did another backup via Time Machine just in case though.