Yes lots of wiring goes behind the back of the head unit. Blend motor wiring, HEVAC multi plug wiring, windows, mirrors and on a LHD car the wiring for the instrument cluster would head pass that way too on the way to the BECM.
Here's a quick pick courtesy of Wiggy and his Blend flap freeing method post....
If any of those wires have been broken or pulled out then that will be the origins of your problem. Unfortunatley the best way to look will be to pull all that part of dash apart so you can see everything clearly (see the blend motor "How to" posts) and get ready to start splicing. Good luck.