My rear wiper stopped working. Thought it was the motor. Took the trim off whilst I ordered a second hand one to replace it. A week later, the boot won't open. When I lift the boot open handle, the rear wiper now comes on and the boot won't open. No obvious damage to anything. My local friendly garage says it's an electrical problem with the wiring in the boot, but they don't have time to look at it for now. Any thoughts on how I can trouble shoot and fix it?