OP - I would reach out to MasterVolt directly. They have been in the marine power business for a long time and may have resources near you that can assist you.
This is a data buss controlled system that may require specialist knowledge and tools like a data buss reader to properly troubleshoot.
Like most Lithium systems, it is not a simple alternator/voltage regulator/battery system like you would find in a normal vehicle.
We live our Tellaro 20AT and wish you only the best in getting this resolved.
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