adj. 1. Non-working due to hardware failure; burnt out. Especially used of hardware brought down by a 'power glitch' (see glitch), drop-outs, a short, or some other electrical event. (Sometimes this literally happens to electronic circuits! In particular, resistors can burn out and transformers can melt down, emitting noxious smoke. However, this term is also used metaphorically.)
2. Of people, exhausted. Said particularly of those who continue to work in such a state. Often used as an explanation or excuse.
"Yeah, I know that fix destroyed the file system, but I was fried when I put it in."
Esp. common in conjunction with 'brain':
"My brain is fried today, I'm very short on sleep."