TAn item in our Frigidaire upright kept the door from closing. We were unaware of it until I notoced it and the freezer was defrosting. I delat with the food, closed the door, and it began to freeze again. Approximately 5 days laetr when I opened the door, it had stopped working at some time and was defrosting. It was running, but was never able to begin to freeze a small amount of water placed in a cup in the freezer. Several hours later, while we waited for the water to freeze, the top of the freezer was very hot to the touch. At that point, we unplugged it. After pricing new freezers, we want to repair this one as it is only 4 years old. Before I schedule a visit, can you give me an idea of possible reasons for this to have occurred so I will be knowledgable before the service rep arrives?

Re:" the top of the freezer was very hot to the touch."

Check if the defrost element is staying always on, it looks like a shorted defrost thermostat.
If instead there is ice on evap coils located behind the freezer, ten the problem is still defrost system, but the thermostat is open.

Check if the compressor is starting, if compressor does not start at all, then that is the problem, if compressor stays on all the time, and does not cool, then you have a gas leak from some point on the coils.

Before calling for repair try doing a complete defrost of the unit by leaving it to defrost overnight.

If the fridge restarts cooling, the problem was the defrost system. If problem comes back after few days or weeks , then the defrost thermostat will still need to be replaced.

You can find parts and diagrams for most models using the link below:

Where do I find parts and diagrams?

Regards