Refrigerator/freezer stopped cooling during a heat wave
Turning the thermostat to a warmer setting should not have caused the machine to quit cooling. Actually, the engineers give you far less leeway than you might think.
The controls are more in a class of fine tuning, otherwise people would be getting themselves into trouble. The manufacturers simply design the warm and cold parameters in a fairly narrow range.
The best setting is normal. When away, the machine will run far less simply because of no door openings. Opening a door lets in large amounts of air every time it's done, which is where your cost to run it exists.
Two things. One, if the temp in the kitchen exceeded 90 degrees for any length of time, you are operating it beyond it's design range, however two, it sounds as if the thermostat hung up, causing your issue. You may want to have it replaced, but it would be useless to call anyone when it's performing normally.
There is no test on thermostats other than by observing their action when the machine is not operating properly.