I have Horizon Elite 2.0 treadmill. A few months ago, during a workout the belt hesitated twice without stopping. Last week it totally stopped during workout & will not start. The dashboard lights up & incline works, but when I push start, there is a "click" & that's all. Removed the cover, did the drill test, all good there. There are 2 lights on the controller board before I push start, then after there is 1 more light on right side of board. We replaced the triac but did not help. 2 pics attached to show you the lights on the board. Tested voltage everywhere, I think. TIA

 

It may be a wild goose chase, but it'd be great to have the service manual. Even if there is one, it may be hard to find.
Your best bet may be to search on your model, and also on any identification you see on the board, in users forums and such. If there is a common mode of failure, someone before you may have figured it out.

As you search for the board, keep an eye out for repair services or someone that's selling the board. A full replacement feels wasteful but may save you a lot of headaches overall.

 

When you push the button and hear a "click" search for that relay and inspect it and the circuitry.

 

When you push the button and hear a "click" search for that relay and inspect it and the circuitry.

Checked it. After replacing the triac for a second time the board was overloaded and there was a smell like motor overheating. I now think it is capacitor and ordered 2.