With a no-grid fault the inverter is not recognizing the AC grid. This could be because there is NO ac voltage, or the internal measurement system of the inverter is broken.
To verify which this is, measure AC voltage directly at the inverter, then verify if the display matches the meter readings. If they don't then you need an RMA.
If there is ZERO ac voltage then the inverter is reporting that it does not have a grid. Determine what is causing the AC voltage to not be present (AC disconnect, AC breaker, No power, etc).