PS4 controller is dead - Battery and USB port already replaced

As described in the title my PS4 controller is dead. The battery is charged, but the LED’s don’t turn on, even with USB cable connected. I already replaced the battery and I also replaced the lower part of the controller (the one with the USB port) with one of a working PS4 controller, which brings me to the conclusion that the main part of the controller (the one with the motherboard on it) must be damaged. I couldn’t find any visible damage. You should also know that, after I took the controller out of the closet to start repairing it, after I put the plug in, the controller worked once with LED’s blinking, but not anymore after I pulled the plug out.

I looked all over the internet to find a guide on how to repair the motherboard or anything related but I couldn’t find anything. You are my last resort. Thanks in advance <3