You kinda are not in the proper forum as this place is for class B motorhomes, but a fridge is a fridge.
I would Google up a troubleshooting list for whatever model of fridge that you have.
A guess: As the boiler gets hot and no cooling happens it would seem you may have a cooling fluid blockage or leak, both issues terminal for the fridge. The fridge must be operated pretty level or it will be ruined, in fairly quick order usually measured in minutes.
Tick tock, baby(Ironbuttal)
2000 Roadtrek Chevy 200 Versatile(sold)
'98 Safari Trek 2480
Just for fun:'15 Kawasaki Versys650LT
Perfection is a fantasy, though improvement is possible(Wifey).