Gamepad is completely dead

Hi. My Wii U gamedpad is completely dead. I have tried to take out the battery for a few hours and tried to start it without result. The battery has power when I loaded it on the side and measured the voltage in it. Now I screwed apart the gamepad, but nothing is loose and I can not see that any circuit has burned. Is there a fuse in the gamepad that could have tripped? Where? I suspect otherwise there is a circuit board that has given up but which when the gamepad is completely dead? I do not want to spend money on a new one when I plan to buy nintendo switch later next year. Hope you can help me to solve the problem. Sincerely, Raoul