I seem to have lost access to the GUI of one of my CMM5 controllers. I tried clearing the cache and using three different browsers, but to no avail. I did get a quick look at a message that popped up when trying to access with Chrome: "LuCI Lua Configuration Interface"
I can still login via SSH, but I'm just not very familiar with the commands to be able to function.
Other then not having the GUI seems to be working just fine, GPS sync is fine and all APs are powered.
Sure enough Brook was right, bad SD card. Looks like the latest firmware does fix this, so I sent a new controller out with the latest version of firmware, brought the bad one in, replaced the card and am bench testing field upgrades.