Why is my freezer/fridge stopping randomly

So I have a Whirlpool refrigerator (GT9SHKXMQ02 - no icemaker) which is not cycling properly. The thing that is a bit odd is that when I either tap the bottom of the freezer or on the controls housing inside the fridge, the unit starts up and brings everything back down to deep temps for 24-72 hours, then it may quit again. Despite no signs of water or frost-covered coils, I replaced the defrost control board anyway at the suggestion of a tech. The situation improved temporarily but has now returned to the same behaviour, less than 8 weeks later. no water on the floor, both coils seem to be clear, fan and compressor sound fine when they are running.

I’m aiming to tackle this within the next week, and looking for specific things I can test/fix:

1. can I ohm anything out or check voltages to confirm if stats or sensors are working right? already planning to check compressor cap but that shouldn’t be the cause here… is it worth checking the amp draw on the compressor?
2. looking at the parts list, what components should I look at swapping out, and in what order? aside from the def ctrl board (already replaced), there is the temp control stat, the defrost stat, wiring harness, etc…. thoughts?
3. Anything else I should check?

Thanks!