I had ran tests to determine if it were the defrost timer or the thermostat control.
I had continuity at the original thermostat but the DT wouldn't start the compressor and fan.
So, I replaced the DT. Functioned properly for 12 hours or so and back to warming up.
Tested thermostat again and found it was faulty for good this time.
Disconnected the thermostat. Used a jumper wire between the two wires (neutral & hot) and the unit started up and cooled overnight.
Replaced the thermostat the next day. Kept the new DT in the unit and kept the old one just in case.
Freezer operates flawlessly now keeping temps to -10°f after adjustment. DT Functions properly as well.