GE side by side not cooling after replacing parts

Side-by-side GE not cooling freezer or frig. Not cooling at all.
Both fans working - evaporator and compressor. I've checked the defrost heater. It's good.
I've changed out the control board, both freezer temp sensors (thermistors), the defrost
thermostat. Still nothing.

I've read about a compressor start relay. I don't hear any clicking as some have
said accompanies this problem. I can't tell what the start relay is actually and when
looking at all parts available for my model I don't find a part called the "start relay."
Is it possible some models do not have?

I'm suspecting the compressor itself at this point. Don't know how to test. I realize
need qualified repairman to replace. At the point after changing all these parts that
it must be the compressor so need to decide whether to hire service to replace or just
dump the unit for a new one, which seems considerably more expensive than replacing
compressor. Don't want to pay for compressor then that not be the fix.

Anyone have suggestions?

Thank you.
.sam