Xbox One Controller - Right Trigger 'Stuck'

The issue I'm having is that the right trigger is constantly depressed, even when it is not being touched. It is not a sticky key or physical depression, but a virtual one. Just to be clear, the trigger is in the resting/open position. To verify this, I plugged the controller into my PC for troubleshooting on gamepad-tester.com and it also shows the right trigger being depressed, even when it's not being touched.

I have opened up the controller and cleaned it out thoroughly and checked to make sure there were no obstructions in or around the right trigger. It appears to open and close normally and looks identical to the working trigger on the LHS (nothing damaged or worn down).

I am about to give up and throw it out unless someone has other ideas?

I read somewhere about possibly being caused by the magnets out of alignment. If so, would I need to cut open the rubber covers to inspect inside?

TIA