I had had the same problem 4 or 5 years ago and spent close to $200 to repair it.
I did have the slip from that repair with part #'s so I went ahead and ordered a defrost timer and thermostat.
You-tube had plenty of videos on replacing those parts and even before they arrived I was able to add a switch and bypass the broken thermostat and start a cycle manually with the timer. (which it seems was was still functional).
Between that and cycling some ice packs up from the still working freezer I lost very little food.
The service from here was quick and accurate, I got real OEM parts in a short time.
Thank you.