GE Profile Fridge stopped cooling, now its cooling again.

Here is the sequence of events:

1. Main board stopped working 4 months ago (it took a couple days for it to fully die), After 3 days of power off, I replaced it with a new board.
2. Three weeks ago, the fridge started making a whining sound when the normally quiet compressor was running (only sometimes, though).
3. Ten days ago, we woke up and the fridge was 58 degrees and the freezer was 25 degrees. The lights worked, the compressor was running - but still making that whining sound. The air coming out of the vent behind the ice maker was roughly 48 degrees.
4. We were leaving on a trip that day, so we emptied the fridge (removed the ice, too so it wouldn’t melt) and turned off the breaker so the fridge was completely off.
5. I came home last night from our 10 day trip, and turned the breaker on and it sounded like it was running normally. After 7 hours, the fridge dropped to 42 and the freezer to 7 (set temp is 41 and 2). After 4 more hours, it is at 40 F and 4 F. It sounds normal, but occasionally it makes that whining sound.
6. GE Profile model is CFSP5RKBD SS, purchased in 2013, says made in Mexico.

Does anyone have any idea what could be broken? Anything else I can do to help you diagnose it?

Update, 1 week later:

The fridge and freezer seem to be working fine, and I haven’t heard the strange noises. I talked to someone who thought it could be the defrost heater that could be broken, and he said it would appear to work normally until there was too much frost on the coils, and then it would fail. He said to take a look after a week to see if there was a lot of frost on the coils behind the freezer. So, I opened it up just now (and confirmed that both fans were working). and saw some frost on the coils. I don't know if it was a lot or a little, since I don't know what to expect. Here is a picture

Update 2 (3 weeks later):

So, the fridge stopped cooling again. During the day I heard a fan which quickly sped up and down, and when I opened the freezer door, I confirmed that the fan changing speeds was the evaporator fan in the freezer. When I say it changed speed, it happened fairly quickly (like in under 0.5 seconds) and would hold it there for about 5 seconds then drop back down. Around this time, the temps increased about 10 degrees to 10 F (freezer) and 46 F (fridge). Then at around 9pm the evap fan stopped completely. I confirmed this by removing the food from the bottom drawer and taking off the small panel. I looked in the hole with the fan blades and there was no ice buildup on the coils, and the fan moved freely with my fingers pushing it. I turned off the breaker to the unit for about an hour and turned it back on and still no evap fan spinning, but I heard the compressor working away. I kept it on for about an hour, and then the evap fan started up again. Overnight it cooled the units to their proper temps.

One other note is that over the past few weeks, I’ve been monitoring the temps carefully with a standalone pair of remote sensors and it does vary quite a bit. The freezer ranges from -9 to +10F over the course of a few hours (without us opening/closing the doors), and the fridge ranges from 33 to 43.

What’s your guess - is my 6 month old main board faulty? Should I replace only the evap fan? If it is my main board, then is something in my fridge causing it to break?

Update 3 (problem solved):

See some of the comments below, but I checked various voltages and thermistors and decided to buy a replacement evaporator fan motor. I installed it and have had no troubles for 3 months since then! I can also confirm that the temp in the freezer does vary by 20F over the course of a day, which I have learned is due to the heater which removes all the frost from the coils.