I had a similar problem but in a truck. Under warrantee a major circuit module associated with the main computer was replaced.
However, I also suspect that the battery had an intermittent shorted cell. That died and was replaced shortly thereafter.
However, I do agree that the bad ground would be the main suspect, and making all connections clean and tight would most probably fix it, plus ward off future problems.
MOTHER SHIP Winnebago View 24H (2007 Dodge Sprinter 3500 Chassis, 2008 Body)3.0 L M-B Diesel V6 bought used with 24K miles. Toad: ROCKY the Flying Squirrel.