It seems odd that neither the Aquahot nor the Atwood heater can deliver hot water. That points to maybe some valve or Tee that is common to both systems, rather than a Atwood heater problem.
Has the Aquahot worked ok for hot water before this?
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