defo the pump at fault here - water has got in the rear light and soaked the poor thing

take of the cover from the base if you can and try let it dry out natually next to a radiator, hopefully it will dry out and work again, else a replacment is needed
you can manually open the flap, from inside the boot first aid area, by pulling the pin, try a search for the info, or let me know I will post a guide for you
vag-com would not show the error, as there is no computer in the pump, then again the will have a convenience module, as it has an alarm?
thanks
p.s. yours should work, to open the flap
