Kendall SCD 700 show error E6

The service manual is available here.  It indicates a software error of some kind,"Upon startup, and periodically during operation the microprocessor performs diagnostic tests. If a software error is detected, this alarm will be triggered"

 My first thought would be CPU board, but that is just a guess.

I was having trouble getting access to many pages and every time there was this error of E6 showing up. The above-mentioned manual really helped me to go through the mc rockers patches configurations. My CPU works so effectively now!