This was an easy project that should have taken maybe 15 minutes max. The most difficult, well not really, but aggravating is making sure that the inside larger panel lines up with the smaller top panel that contains all the electronics and connections. I would put that top smaller panel in first, secure it in place just a few turns of the 21 side screws and then place the largest bottom panel in place making sure that the tabs on the top panel are inside the edges of the bottom panel. This is easiest to do if the door is opened all the way and the panels stay flat.