Its more likely to be a mechanical issue, if its moving the switch and motor are working, is there and clicking or crunching sounds, the window actuator teeth may me worn, or window glass jamming if not in the holder correctly. The actuator may be going down but leaving glass half way.
I would start by taking door card off and seeing whats happening when you press the switch.
Edit: Sorry may have misunderstood, thought window was lowering to half way but after re-reading think you are saying it is not working at all now and stuck half way.
I dont know what year your TD5 is bit here's a 2002 on wiring diagram.