Once again the dear trunk

Moin, I’m new both here in the forum and as a Phaeton driver. Unfortunately, I already have the first problem to fix directly. Vehicle: GP0 07/2006 V6 TDI, very well equipped, also with the automatic boot operation. Very few kilometers, battery was recently empty. Problem: The boot flap reacts to nothing. I can open and close it manually, but neither the switch in the door, nor the key, the button in the VW emblem or the button to close it. In a closed state, the lock does not lock either. It is permanently “folded”. Previous steps: First, I have read out and deleted the fault memory via OBDeleven. Didn’t help. Then, I have the trunk covering in the sure belief that it is a cable break. However, all cables between rear flap control unit and lock are continuous. This is what the error code after deletion says: 00318 – Supply voltage for control unit for tailgate lower limit was below sporadically 01699 – Engine for ZV, tailgate mechanical error sporadically 00896 – Locking unit tailgate unplausible signal sporadically guess: Maybe it really caught the control unit for the tailgate…? Has there been another good idea of you experienced Phaetonists what it can be and how I could check it out? Greetings, Dennis