If your Xbox One Elite Series 2 controller gets no power via battery or from the USB port, disassemble and check the component labeled BQ24250 on the digital board. This is the battery management circuit and produces 3.3V for the controller.
Test it with the USB cord plugged in. Then verify:
- that you have VBUS going into the BQ24250
- that you have output voltage past the inductor
- also verify you get a voltage on the battery terminals.
Be sure to remove the voltage sources before you solder.
You can order the BQ24250 directly from TI, Digikey and Mouser.
I haven’t encountered a power supply issue on an Elite Series 2 controller, but “by-inspection”, the power management IC would be the first place to look.