Fuses that blew are reverse polarity. Rih was wired correctly. I would verify that the batteries are wired correctly. Possible they are not wired is series.
Connect back up as were originally connected. Then pug in the rig. Verify voltage at the batteries for converter voltage of around 14 volts. Not present check converter voltage. If converter is outputting 14 plus volts.
Does the batteries charge when connected to TV?
Correct color coding for 12-volt DC is red for positive and black for negative. Yes, some are not wired that way. Would be a good idea to start marking red positive and black negative.