I'm not aware of an accessible fuse, though I'd have to look mine over to be sure. The owners manual doesn't address a fuse either. The 12v power cable shouldn't be more than 2 amps maximum.
You don't mention your location for a possible authorized repair shop, or whether your unit is under warranty, or if you purchased it used, so depending on all of this some other avenues of support might be available.
I'd call their customer care. Are you using the right phone number? (402) 385-3051
If so and you're not getting through, or they're not returning any phone calls, you can write a service request and fax it to them at (402) 385-3360. Or, there's the old fashioned snail mail:
One Mill Road, Industrial Park
Pender, Nebraska 68047
Hope this helps some..
Jeff & Sharon Wise
2021 Forester 2151LE-<2020 Jeep Wrangler Sahara
Dripping Springs, TX