Another thought... Have you tried to retract the spoiler all the way with the switch on the dash while someone else GENTLY pushes on the spoiler for that last few inches to get to full retraction? If that works you know it is a physical resistance problem somewhere the mechanism may be recognizing and shutting down. By adding a little pressure to the spoiler while retracting that would counter the level of resistance the mechanism is sensing. May be worth a try. If you were to get it fully closed by this method it may break lose whatever is causing the resistance. I can't guarantee but I highly doubt if it were to fully close with a little pressure applied that it wouldn't open again. That is a risk to be considered though. When my spoiler started acting up due to ABS/BAS issues that are totally different from yours it would deploy and then get stuck in the extended position and wouldn't retract except with the manual switch on the dash after a shut down and restart. I retracted it fully with the switch and then pulled the fuse to it as I'd rather it be fully retracted permanently than keep on deploying and stay that way going through that BS over and over until I got the ABS/BAs fault fixed that turned out to be a wheel speed sensor gone bad.