Replacing a "dead" M215 is fairly simple. The plastic special orange tool shown in the video is/was available on eBay; it is required to disassemble the connections going to the old inverter. If you find a brand new M215 online, get the unit's serial number; phone Enphase & they will verify that the unit has never been installed/registered; then purchase the unit. When you buy a new inverter from Enphase, the 25 year warranty starts at the time of installation, OR 90 days from the date that it was shipped. The unit that I bought online was brand new, but "used" 1618 months of the 25 year warranty just sitting in it's box; if you get it at a great price, the "lost" warranty is so meager compared to the cost of a new inverter from Enphase. As shown in the video, the DC connections going to the solar panel CANNOT be mixed up; they will only connect one way. When you make the connection to the rail where it joins all the other inverters, just be sure to look for the arrow on the connectors and ensure that they line up before pushing the connection together. Be sure that ALL connections lock into place as the plastic tabs click shut. It appeared to me that the only connection that could be reversed was the AC connection at the inverter. I found no arrow and the connection appeared able to connect 180* either way. I asked the Enphase rep on the phone and she didn't know if it was reversible, or not. If any viewer can answer that question kindly do so below and I will add additional info to these instructions. When doing my first inverter in 2020, one of the end clip bolts was locked in place; I was using a 1/4 inch socket & drive and had to lock the vise grip pliers on the round surface of the bolt AND use the 1/4 inch drive as well to break it free. Be sure to have a 3/8's drive 6mm hex socket/ratchet before attempting to change an inverter. Be careful on the roof; Covid19 didn't get you, so don't fall and break your neck. The entire job is fairly simple with the right tools.