Been through 2 technicians; no firm diagnosis but lots of $$ spent with not even a strategy;

I'm stepping in now and asking for help - Issue - Everything was operational-cold and I started to hear a clicking sound coming from the upper-center mechanical area on top of the unit. Display showed temps, etc but clicking continued, then all noise stopped - control panel lights went out - Everything went warm over several hours. Note - all interior lights and water dispenser continue to work as normal. Display is blank and compressor not running when powered on.

Tech #1 came out and diagnosed a bad inverter (W10629033) and 'control board (2318054). He replaced above with new parts and compressor failed to kick on. He said those parts were not the problem and I likely had a failed compressor (since temps did not slowly get warmer). Purchased parts were returned and original parts were replaced in unit. Tech 1 did not work on compressors so no further help from him.

Tech 2 (commercial refrigeration guy) evaluated and was able to get compressor to power up by by-passing the boards. He says the problem is more likely in one or more of three boards....
2259350 (power/transformer)
2304135
2316545 (alternative board to the board tech 1 attempted to replace 2318054) Tech 2 says Tech 1 did not source the right board based on the model #.

All three boards add up to over $900 to replace. This is an expensive unit to replace >$7K so I'm really motivated to figure this out.

I'm inclined to replace the power/transformer board first and see what happens. Then replace each successive board and hope for the best?

Any suggestions or alternative debug methods would be appreciated. Anyone had similar/same issue with this built in model KitchenAid? Thank you!!