I would say that the CLICKING you hear is the relays inside engaging or disengaging, which means something is working. Since the motor slewed very slowly and then stopped, I would wonder if:
1] The backlash is too tight and the temperature has caused it to bind more.
2] The extreme temperature has allowed some moisture inside to freeze and bind the motor.
3] You have a high DC line loss and low current at the motor.
4] Your relay contacts are dirty and arced and not making good contact.
5] You have a bad solder connection internally.
6] You have a bad motor.
First thing I would try is to take the receiver out to the motor and connect it with a 2 to 4 foot RG6 cable and see if it still acts the same.
If that corrects it, then you have a bad cable/connector somewhere. If that doesn't pep it up, then it must be within the motor.
Try warming the motor with a hair dryer (preferably on a warmer, sunny, non-windy day).
If you still cannot get it to slew, you might just have to take it down and troubleshoot it in the shop.
Bake it in the oven on the absolute lowest heat for a couple of hours or so. That will dry it out inside completely.
Then experiment with it and open it up and examine all the circuit traces, solder joints and the backlash adjustment, etc.
RADAR