Viiking

No tools needed. Less than 5 min job if you have quick fingers. If you take it easy or your body doesn't bend that well to look closely what you are doing, then probably some more time.

Still original factory battery? If so, change it, I guess. It's been going exceptionally well for it to have lasted this long. There is nothing to lose by doing this.

From manual: Adjusting ›Stop the lid in the desired position (electrically or manually). ›Press and hold the button B » Fig. 45 on page 60 for longer than 3 seconds. The setting of the lid top position is confirmed by an acoustic signal. Delete ›Carefully raise the flap manually to the limit. ›Press and hold the button B » Fig. 45 on page 60 for longer than 3 seconds. An audible signal is emitted. The original position is deleted and the top lid position is set. I guess you shouldnt push boot lid manually to desired position but let it raise electrically and stop electrically (push button) on manually (by hand) and then save. Right now as you rising lid only manually then car deals with it as you would like to delete position or is just confused and wont save anything. Maybe. Or try saving a position other than max open but something other than the current position and if that is successful then try saving max again.

Works like a charm!

When the tailgate handle/switch of my car turned out to be faulty, the hatch closed by itself after some time or closed immediately when I opened the back door! Not exactly the same concern more or less similar. Changing the handle solved the problem.

If you have still original battery then most probably it is nearing the end of its life. I had recently similar symptoms and one day the 6+ years old battery was died. After replacement all OK.

It is possible to open/close all 4 windows simultaneously via key fob by longer pressing of unlock/lock button.