Audio Systems: no picture or anything just beeps, headrest monitors, stock radio

Question
hi i have a 2006 ford explorer and i replaced the stock radio with a jensen ts9020 and i was going to hook up the reverse camera and it needs a power and ground wire so i ran 1 out of the same wires that power the head unit well while the dvd player was playing i cut the power wire that i had spliced into the head unit and the head unit shut off as well as my headrest monitors and neither will power up not even after i reconnected the wire  i checked the fuses in the truck and the fuse in the back of the head unit and theyre all good i pushed the reset button on the front of the head unit and nothing it beeped 3 times but wont power on. when i push the power button on the head unit it also beeps but doesnt power on. also non of the lights come on. i rehooked up my stock radio and it works perfectly so i know its not the truck its the jensen my headrest monitors wont power on either can you help me figure out what is wrong? i think its gunna be something dumb that im overlooking but i need some help  thanks

Answer
Hi Chris,
first off the reverse camera should be powered by the reverse switch output to the reverse lights so it comes on automatically.
Why the hell did you cut the wiring while it was playing? If you are working on the electrics you should have the battery disconnected first.
Sounds like you have upset the head units programing and as you have swapped the unit with the stock one and back and it's still not working I think you have a major problem in the Jensen. The problem is something dumb, you cut the wire while the set was live!
Peter