I installed 3 of the 90s on a customer tank. Once a month one or more will disconnect and stop working. Sometimes, just a power cycle will bring them back, other times I have to hard cycle them.
You can do this without taking them apart. It is difficult with just two hands though. While holding down the settings button, you very quickly disconnect & reconnect the DC plug in quick succession. Just long enough to see the red settings light flash on/off. After the third reconnect, release the settings button. The light will then reconnect and run your program. Until it fails again in a few weeks. PITA, but better than taking it apart.
Personally, I think their skimmers are just as bad as their lights. In Red sea sumps, you have to put them on a 4 inch platform to keep them from overflowing. I have not had any issues with their tanks so won't speak to that.