Hokies 3030, I had a similar issue with a TRX-2 (+ a Waiting for Main Unit message) and was given the following instructions from Whistler to clear it. Hope this helps...
Few steps to correct this error.
1) Remove all cables from the scanner
2) Press and HOLD IN the power button for at least 60 Seconds ( use timer to be sure as time is critical to getting this part correct.
3) Plug in power cord: error gone, press power button to turn on scanner. If error remains
4) Unplug power. Remove Head from main unit and reinstall. Plug in power cord: error gone, press power button to turn on scanner. If error remains, repeat