This is a really a problem solved, but one to be shared. The on screen error report may be misleading. The online documenation has the error listed and was the gide to solving the problem. Qudos to Victron for this recently updated document.. Our customer had an error 54 appearing on a Multi RS. The problem was the two 240V 15A white ceramic fuses inside had blown. Its a very simple fix. Our first on a Multi or Multiplus. Because the Multi RS is planar, the ride through current on overload or inrush is less than the metal donut transformers. As a result it is probably more susceptible to blown fuses. Can the trusted community comment on this hypothesis?