What do you mean by quit? Dropped out of steering, won't hold course, respond to remote or buttons....?
Check for power to all pieces, then go to your manual for the "calibration" procedure...it is pretty straight forward - do some circles one direction, then the other, then a figure eight and the computer will be just fine.
All that being said, the pilot should work even if not properly calibrated...just may not be as finely tuned or smooth as you would like. If the pilot is in fact not working, then you will need to do some trouble shooting (power, connectivity, what IS working, what isn't, flux gate/compass, etc)
In my experience, you are almost better to contact the factory, as the tech will just do what I have described above and then declare that part A is defective, and will need to be ordered, and give you a bill of many $$.....which you can do in conjunction with their tech support.
Hope this helps get you started.