The same compressor prob, but with a twist... (yeah, clicking & all that too)

Model Number: GSL25JFPH BS
Brand: GE
Age: 6-10 years

I have a 12 year old GE fridge & I love it as it's served us well, but we've just run into a hiccup I can't seem to get past.

A few days back my wife heard the dreaded "click click click" from the rear of the fridge, then after a minute or so it began to defrost. Reading that the likely culprit would be the Motherboard I ordered a new one & replaced it, to no avail - it actually by the point was running warm. I tested the compressor with a multimeter & everything tested exactly as it should, so I assumed the next likely culprit would be the starter relay, so I replaced it with a 3-in-1...

the compressor still will not turn on! Ideas?

Is it perhaps stuck in defrost mode? Bad defrost timer? When it goes into defrost compressor does not run.