Hi,
Per the Hayward website (see below). If resetting all the breakers does not fix the issue then I would think it would be a bad board. We do carry the HPC-4 E-command Main Board here - Hayward HPC-4 E-command Main Board (unfortunately we are currently out of stock, you can click the Notify When in Stock Icon on that page to be notified when we receive our inventory) The replacement of the board should not be too difficult we do have this Video on How to Replace an AquaRite PCB Board although it is not exactly the same as the E-Command you will get a general idea of what is involved in replacement as the process will be similar.
Why does the screen read “Communication Error”?
This means there has been a disruption in the transfer of information from the main PCB to the display(s). Deactivate all the breakers in the bottom of the control box and wait 5-10 seconds, then re-supply power to the control and check the display. If the problem has gone away the issue should have been cleared. If the problem persists, contact Technical Service for assistance 908-355-7995 (Monday - Friday, 8:00 am - 5:00 pm).
Thank You
Patrick
www.inyopools.com