Keyless handfree problem

Hallo, the opening and closing function using the sensors on the handles no longer works. The problem is random. Sometimes it works other times it doesn’t. At first it was not possible to open the vehicle, but locking worked. Now when it stops working it is no longer even possible to lock the vehicle. Any suggestions on how to solve the problem? The remote control battery was the first thing replaced.

In case anyone is interested or is in the same situation, the problem was caused by the service battery of my E-Tense (the battery is under the trunk on the right side) which was flat. The battery was recharged and the problem no longer occurred.