The part that is responsible for communication is a combination between the trackpad and the mainboard. If the mainboard doesnt recieve a response from the trackpad then it will not sync and the cable is a common failure point. [br]
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So if your controller won't pair you may notice that the blue light blinks slower. If this is the case then you should replace the ribbon cable on the trackpad (requires soldering the 2 pads on the haptic motor) or replace the trackpad assembly.