Allen,Just to clarify the system is now fully functional by replacing the Comm Express on the Base Board, correct.If something like this happens again it could be the PSB, BB or backplane. To trouble shoot this to determine which is causing the issue you would follow most of the steps you where provided through the trouble shooting process.1. Move the PSB to another station.a. If it is able to read on a different station and different BB then it’s not the PSB.b. If it doesn’t read you will need to trouble shoot the PSB. Possible U1 or Cypress or possible connector.2. If your PSB is ok, Insert a known good BB into the system with the original PSB that you just verified functional in step 1.a. If you can read then you have a faulty BB and follow some of the same trouble shooting just did. Beyond he Comm Express 3. If it still doesn’t read then you have some issue with the back plane, typically some sort of connector damage or insertion issue. Would be good to move to another slot to verify because it also could be an issue where the backplane is not fully seated against the back wall causing the PSB to not fully seat.