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?