I can try and help, the RM2852 is just the bigger version (longer and more internal space) of the more popular Sunline RM2652 I do believe.
We need to confirm a few things.
1. Make sure I have this correct. You said the fridge was on "Auto" (the yellow Auto light was on) and running well plugged into 120 VAC shore power. Yes/No?
2. Then you saw the "check light" come on and things were not working (no cooling) Yes/no?
The "check" light is only to indicate a gas flame fault. It does not mean the electric stopped working, it means there is a problem with the gas part of the fridge. Even if you did not switch it to gas, the system auto switches from 120 VAC electric to gas when you lose 120 VAC.
If you did not take the fridge out of Auto, then it points to the fridge control board stopped seeing 120 VAC and it switched over to gas mode. Gas tried to light and it failed 3 times trying to light and then went out on safety and turned on the check light.
If you try to run the fridge on gas, (manual) and hear no clicking of the igniter after a few minutes, then it can also mean the main control board has issues. OR the gas igniter has issues or both.
If what I said above fits what you are seeing, this is going to take some electrical troubleshooting to sort out what does or does not work. Do you have a volt/ohm meter and know how to use it? You will need to read 12 VDC, 120 VAC and do an ohm resistance check and be electrically friendly enough to feel good about doing this type of electrical testing as there is risk of shock if done wrong.
If the electrical testing is too much for you, then if you have an electrician friend they can help OR a camper repair dealer.
Also, that fridge had a recall on it. It is a safety recall and is free and still active. I do not see the recall parts in your pictures. Any Dometic repair center can do the recall for free for you.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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