When in doubt, call a Mitsubishi Diamond Contractor. They have the MNET TOOL (PAC-USB-001) diagnostic software that can map the network and identify exactly which byte of data is corrupt.
When power returns, the outdoor unit will take 3 to 5 minutes to initialize. You will hear relays clicking and the fan might spin slowly. Do not touch the remote during this time. The indoor units are polling the outdoor for an address. mitsubishi multi communication system reset
But for the homeowner or facility manager stuck with a frozen AC on a hot day: Nine times out of ten, that is all the "reset" your Mitsubishi Multi Communication System will ever need. Disclaimer: This guide is for informational purposes. Working with electrical panels and PCB boards carries a risk of shock or equipment damage. If you are uncomfortable performing these steps, hire a licensed HVAC professional. When in doubt, call a Mitsubishi Diamond Contractor