Hi there and welcome!
Most likely what has happened is that your safety rollout limit switch has failed. Yep the switch you provided the link to.
It is located here inside your smoker and is like the size of quarter:
View attachment 644754
If you are lucky you have a panel on the back of your smoker like the top one here labeled "Rollout Switch Panel":
View attachment 644755
Under the panel it will look like this to get to the switch:
View attachment 644756
If there is no panel then you can:
1.) Cut a panel (I highly suggest this)
2.) Remove the back and get to it (way more complicated)
The part you want is a KSD301 150C degree switch. These switches are pretty low quality and melt down all the time so having more than 1 is pretty much mandatory. Here is a link to ceramic ones that should not fail as easily as the plastic ones like the one from the
Masterbuilt site. IMPORTANT: Get this exact one!!!! There are 2 styles of switch that look the same but are not built the same and the other style will NOT work. This is the proper style, is ceramic, and is 150C so buy something different at your own risk :)
If you don't have a panel just look on the inside and measure with a measuring tape from the ground up to get an idea of where to make a cut. The sheet metal on the back isn't too thick so if you drill a hole just through the metal and then use pointy tin shears/snips you can cut into it to access the switch cover box you see halfway up on the right hand side of this picture (again, don't remove the back, this pic is showing u the switch cover box):
View attachment 644757
That box unscrews from the 2 other screw heads you see on the inside of the smoker.
Once you get to everything and GENTLY replace the switch you can seal it all back up and cover with foil flue tape or high temp duct tape or whatever you want and then you now have access to it whenever you need.
Finally, I highly recommend you get some of these high temp 14-16AWG female spade connectors to replace the spade connectors that
Masterbuilt uses.
The connectors
Masterbuilt uses are pure trash and corrode away in no time so these will be a great improvement with you already in there. In any case it is very likely the connector has already corroded away on top of the switch melting down.
Let me know if you have any questions and I hope this info helps :)