Freezer sides are hot all the time
It sounds to me like the defrost heaters are not turning off.

I can not tell you if yours uses a thermal switch or a timer to cycle them, my guess is for a mechanical switch not working anymore, and stuck in the on position.

I am going for the idea that the repair guy thought nothing about the hot sides/top, because it is normal for it to happen, and he decided yours were just at the on part of their cycle.

The heaters running produces more heat (never saw that coming, did you). The compressor is doing its best to get rid of the heat, but it can not really keep up with the heaters, because of this it runs much more than normal.

The compressor was never designed to run as much as it is doing right now. With the duty cycle now so high, the compressor is running loud. And around we go again.

A full freezer is a happy freezer, never a worry there (if all is working right).