1. Does the customer fell comfortable opening the panel where high voltage is present? If not they need to contact an electrician
2. Verify all breakers are in the on position. Any breakers that are turned off can cause this problem to occur.
3. When reading the error message the number that is displayed next to "Phase Sense Fail=##" is the address for the module that has the failure. The customer needs to verify the following.
a. All breakers are in the on position
b. The neutral for the module in question is landed on the neutral bar.
c. The thermal switch located on the heat sink for the module is plugged into the module
4. If after all these checks, the error message is still present, the customer needs to order a replacement module from their distributor as the zero cross circuit on the controller has failed.