Dang computers!
I haven't had to troubleshoot this, but it sounds like the control board measures the current used by the AC heating element, and what it's reading doesn't match spec. Could be a safety feature, could be a tool to prevent you from using 3rd party parts.
When you replaced the heater, did you replace with a genuine part? Where did you order from, maybe you received a counterfeit part?
Does the service manual publish how many OHMS the a good heating element should measure, or at least how many watts the heating element is rated for (then you can calculate the ohms)?
This will give you a number to look for that a regular multi-meter can tell you. IF the number you MEASURE matches the number published / calculated, then likely the part of the control board that measures current is faulty.
EDIT: found this link that explains what to measure and how to calculate:
https://www.arprv.com/norcold-ac-heater.php
