Just make sure you are unplugged from shore power, turn the USE switch off, turn Chassis/Start switch off, and disconnect the negative cable (which goes to the frame ground, which is also where the ground feeding the inverter goes).
After you complete the above, you are safe to remove, disconnect and install the new inverter.
I removed the inverter bay door first to have easier access for the job (one screw, and slide it out), then removed the 4 mounting bolts and moved the old inverter out for easy access to all the connections, (took pictures to be sure), disconnected everything, and reversed the process when installing the new one.
Your Firefly system will automatically detect the new inverter, but you will have to set your battery type, capacity and charge rate.
It's an easy process and you will love not dealing with the issues and limitations of the old ME inverter!
2018 Palazzo 33.2