did you check your power wires? im a little drunk, so im not sure about anything, but check your power wires... run some wire straight from the battery to the 12V line on your headunit... if that works, then your power wires are Effed in the A somehow... run new ones...
you have to try both 12V and Acc, the headunit wont turn on without the Acc one attached... so if you chuck a 12V constant on that, and it works, it means your Acc is f**ked somewhere along the line...
either wire or fuse... run a new wire from the fuse to the head unit, if that works, that side of the power works... if that doesnt work, the 12V line to the Acc fuse is f**ked...
trial and error is fun
be careful
also, more info helps sometimes
also, i hope that made sense, cause im not proof reading it...