Freezer not freezing and fridge cool

I have 48’ s/s that has stop freezing on the freezer side and is barely keeping things cool on the fridge side. This all started with an Over Temp indicater light that ,when reset, would come back on in an hour or two. The unit is now running in MAX cooling mode to keep things cool. When I run the diagnostic routine I get a "compressor off " code. I’ve tried the diagnostic 4 times with the same outcome each time. I can’t really hear the compressor running but can’t remember if I have ever actuallly heard it although if I put my hand on it I can feel it vibrating . I’m not a repair person but do have an understanding of refridgeration basic through my experience as a mechanic.
Any ideas would be appreciated, I could not find another thread about this topic when I searched but probably used the wrong words.
I’m kind of thinking its going to be a compressor replacement, if so any idea of cost?
Thanks for your advice, and such a long discourse.
Doug