Hi Mark. The issue with the Si5351 Error needs to be handled first. With power off, use your ohm meter to check for continuity between IC2 Pin 28 and JP6
Pin 1.  Also check for continuity between IC2 Pin 27 and JP6 Pin 2. These are the SDA and SCL communication leads between the two chips. And with power on, carefully look for about 3.4 VDC on the cathode end of D1. Let us know what you find ... 73 .. Ron