Elite Wireless Series 2 It doesn't work wirelessly

I have disassembled the controller, to try to desolder the bumpers, but I did not succeed. The problem is that when I mount it again, the controller doesn't work wirelessly, it's sync with the console, but nothing I press on control is reflected on the screen. I have connected it by usb cable to the PC and all the buttons work. I have verified that the two cables that connect the two motherboards are well connected. What error could be happening?

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I have this problem too. I disassembled my controller to clean the button contacts. I reassembled it and everything works except wireless communication. Maybe there's something I left unplugged? I noticed on the back side of the board the sticks are soldered to, there is a header labeled C0 that has nothing plugged into it that maybe I need to plug something into, but I just don't know what.

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