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I finally got back into the shack after almost a month.? And I am glad to say, the uBitx lives!? ?I want to thank everyone for the excellent advice!? ?I started by removing C1 and replacing it with a small discrete capacitor.? ?My plan was to work my way through the capacitors until I found the problem.? ? After replacing C1, the radio was fixed!? ?Other than re-reading all the posts here and taking a few minutes looking at the schematic, the whole repair took about 10 minutes!? ?Thanks again for all the help from so many knowledgeable individuals!? ? This is truly an amazing group!

Curious, that's two bad 0.1uF 1206 caps found shorted recently.
Both of them on the 3.3v supply rail from Nano to the Si5351.
The Raduino has two such caps on the 3.3v rail, and three identical caps for DC isolation
from the three clocks going from the Raduino out to the uBitx main board.
Makes me wonder how many shorted DC isolation caps we have out there,
and what the symptoms would be.

I doubt these caps failed because of abuse, they are operating at a tenth of their rated voltage.
I'd guess poor quality control on the part of whoever manufactured those caps.
Possible that the auto-insertion equipment was handling them roughly
or the boards are getting flexed somewhere, but those both seem doubtful.

I personally found a shorted 0.1uF cap on a Bitx40 main board built at the end of 2016.

The uBitx main board has about three dozen of the same cap, and the rig won't work
if pretty much any of them decide to be shorted.? Some of those would be hard to find.
If we suspect there might be a shorted cap, a good start would be to compare ohmmeter
readings across each cap for a good board compared to the bad board (with power off).
That may not identify exactly which cap if it's on a power rail with 10 such bypass caps
plus bunches of other parts, but could help point the direction to go.

The old thread for this particular story can be found here:
? ??/g/BITX20/topic/81064470

Jerry, KE7ER