The first thing to try with a flaky EMS is to remove 12v power from it to force a reset. Try using your house battery disconnect - that usually does it on American Coach products. If not, you will have to pull the access panel off and remove the 12v hot wire.
Why are you sure it's the EMS? If several 120v things are off, you might have lost one "leg" of your 50A power.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC