Since that display indicates 13V but 0A, it would appear that it is not charging as current would be going somewhere. Am I correct to assume that you have connected to an outside source of 120V, alternating current? If so, I would try turning on something like all of the lights to see if the current indicator reads something more than 0a. The red fault light seems to be indicating something is wrong. A properly operating Magnum should look like below.
In searching the internet, I was able to locate this downloadable
copy of the owner's manual which should help.