1. Have you tried disconnecting 120 and 12 volt power to the 458 for 10 minutes and reconnecting? THAT reboots communication errors on a Freedom.
2. You do NOT have a Converter. The Xantrex is a multi function Battery Charger.
3. If you determine the Xantrex does need a board, on a 13 year old Inverter, I would instead opt for a NEW Xantrex, which will also require a NEW remote panel as your panel probably will not function with the current Freedom's.
4. Is it Possible that your Battery Temp sensor system on the Xantrex is malfunctioning causing your full charge error? Doug