Oh dear - there's nothing worse - I'm so sorry too - try to stay calm - I know I shouldn't be saying that - cos I'm the worst for giving inanimate objects a good thrashing when they fail me.............
At least you have back up but as Hobjob David has said try removing all its power sources if you can - its only a small computer after all and what do you do with a bigger one when it plays silly beggers - take the plug out of the socket and remove electric for a spell (usually at the same time as muttered 'let that be a lesson to you' thro gritted teeth!)(and even threatening gestures.............)(doesn't make a jot of difference to the offending object of course, but it might help to keep you sane .......)
Pauline