Not sure if you've tried a multi-meter to test your circuits, but it could be a fuse. I went to Manuals to look at the 2020 790 manual and it shows one 10 A fuse that covers these items. Fuse 6- 10 A - high beam, low beam, position light, taillight, license plate lamp. If all the other lights work on this same fuse, then a meter would help you troubleshoot it. I know on a car, when your instrument panel lights goes out, it usually means a fuse for the rear lights has blown.