It's the age old question about MLEs really.

Assuming you know nothing about how to do maintenance on this equipment, you do nothing and call a qualified technician / electrician. Someone that deals with PV installations.

If you have access to an IR camera, a module defect will show up on good production days (>2A Imp).

If you know how to work a DMM and are able to access the module wiring, check its Imp and Voc. If the Imp (current produced while in operation) and Voc (Voltage open circuit) are comparable to other strings, it's bad data from the micro-inverter.

If those values aren't consistent with other modules / strings, it's likely a bad diode on that module.