Cannot open trunk flap

Hello, I’m new here and I’m asking for expert help: With my Renault Megane Grandtour 1.9 dCi from March 2006 I have problems with the boot flap. It started with sporadic appearance that I couldn’t open the flap. After some time and driving it went again. Recently it was added that it didn’t close immediately, you had to hit a few times. Have already read a lot in div. forums about cable breakage, plug defective etc. I have inzwis I have removed the boot switch and bridged it: no reaction. Even on a 12 V test lamp nothing happens, i.e. according to my understanding, there is probably no voltage at all to the switch!? Who knows, which safety is responsible for it? Is it in the motror room or in the interior? Who else has a good tip?? Thank you in advance