I had the same problem, alarm going off through the night , tailgate open warning, wiper and washer intermitantly working, so went on some foums and they are very helpful, so i feel i should help others with my remedy.
Took the tailgate cover off ( quit easy ) and straight away see the damp and corrosion, water dripping from the motor, the connection had come loose, found the 'o' ring in the hose was dislodged, put the 'o' back in the bottom of the washer connector, the plug on the lock was very corroded as well ( this connects the central locking ) so can understand the alarm going off.
I bit the bullet and got a new motor from Euro carparts £ 90 ish ( part number attached ) and some contact cleaner £95 alll in all, assembly was 45 mins, and fingers crossed all is ok.
Hope this helps others.
Thank you all.