Some Heartland models have a fuse wired in the wiring (in-line) to the main 12 volt distribution buss bar. Some have a mini circuit breaker connected to this bus bar, with wiring going to the landing gear switch. See the 12 volt troubleshooting section in the "Tools" tab at the top of any forum page; then "Manuals" and then "Electrical", and "12 Volt electrical" sub menu choices. Resetting these circuit breakers with the mini red button can be tricky.