Does anyone now have the final solution for the non-opening tailgate on the V50?

Hello, there is already a parr thread, but nobody has a final solution. With my V50 you can’t open it to the tailgate from time to time. What was initially tolerable is annoying me now, because there is no regularity, except that the moments in which it can no longer be opened become more frequent. Curiously, it happens that I sometimes come a few hours later and it goes up again, sometimes it doesn’t. Sometimes I drive a round and it goes again, sometimes it doesn’t. Sometimes I pull harder at the flap and it opens, sometimes nothing works. I have – after it first came up with the lock with WD 40 (regularly) and had the EInpressure it went well. However, last time the flap can’t be opened any more with every 5th attempt. How are your experiences ? – lock defective ? – electrical equipment defective ? – control device defective ? – sensor at the handle was defective ? Could you find the error by means of reading out and remove doubtless? Entries is not remedied by the dealer?