I get a “DUT mismatch error” from CBPro when I plug in the board and start CBPro. This is assuming you’re using an EVB in the default configuration. You’re not wiring from the field programmer board. For details about wiring from the field programmer board please review the user guide. It provides detailed information: https://www.silabs.com/documents/public/user-guides/ug286-clockbuilderpro-dongle.pdf
4. Check Power: USB Power vs External Power: Can you verify several of the test points making sure you're powering from USB? VddA TP1 should be 3.3V. TP2 should be 3.3V, TP23 should be 1.8V. This would verify that the chip is being powered correctly. If you are getting very different numbers this suggests a power problem through the USB path. If there is a problem here could you try powering the board Externally from 5V supply. The procedure to do this is in the user manual that you've been reading. Again, measure the test points.