Suburban does NOT use a thermal fuse...so no need to look/check it
Suburban does use separate systems for electric and propane UNLESS model is a 'DEL'
That model uses a COMMON DC circuit for both electric and propane (similar to Atwood design but different)
So if you Suburban WH is a 'DEL' model then verify you have DC to On/Off Switches
Check that the High temp t-stats are reset (Push To Reset cover above gas valve)
Left side AC--right side DC/propane
Otherwise post model and more info on what it does/doesn't do
IE: sparks but no flame, flame but doesn't stay lit, AC circuit breaker trips, No AC Voltage at element etc