Is it tripping the main breaker due to a short or is it tripping a GFCI due to current leakage?
You should have a GFCI. That is normally what will trip.
To troubleshoot the issue, first turn off the grill power rocker switch and unplug the power cord from the bottom of the hopper. Now reset the breakkker/GFCI. If the breaker trips again, the problem is either in the outlet, of the power cord.
If the breakker does not trip, now pl;ug the power cord back into the sockket on the hopper. Now try turning the rocker switch backk on. If the breaker trips, you might have a bad switch. Some people have reported issues with the switch. Fortunbately, if the switch is bad, it is easy to obtain a replacement switch and install it, as long as you have basic electrical skills.
If you are good up to this point, try turning the controller on. If it trips, you will need to do some additional troubleshooting.
Turn the power switch off and unplug the power cord. Now remove the screws holding the controller to the front of the hopper. Gently remove the controller panel. Before you do anything else, get a camera and take a photo of the wires connected to the controller. Troubleshooting will involve disconnecting the wire that go to the auger, fan, hot rod and thermocouple. When reconnecting them, you want to be certain the wires go back on the terminals they came off. The photo will help with this.
Remove all of the wires from the controller except the ones that go to the power switch. Then reconnect the power cord and turn on the switch, then turn on the controller. Hopefully, the breaker will not trip. If it does, there might be condensation that got into the controller from the unusually cold temperatures. You might try spraying WD40 on the controller panel to dissapate and moisture. WD40 was specifically designed to remove moisture. However, it is flammable, so make sure the power is disconnected when you do this.
If the controller powers up normally. shut it down again and reconnect the wires one at a time. Make sure the power is off when reconnecting them. Refer to your photo to make sure each wire goes back onto the right terminal. When you connect the wire to the part with the current leakage, the GFCI should trip as soon as you power back on. I know that some people have had issues with leakage around the hot rod. You can try cleaning and reinstalling the part with the issue, but you might need to replace it. Fortunately, replacement parts are available and there are YouTube videos that show how to replace each part.
Good luck. If you still need help, come back and indicate what you have done and what you obaserved.
