More info will get better responses because the 2 brands work differently and have different circuitry
Suburban OR Atwood.
Atwood trips....most times you can't operate electric heating either due to common set of t-stat
Sounds like a Suburban cause you state you can operate electric OK
IF water has been heated with electric it will have to cool down below 110*F before you can try propane due to set points on t-stats (turn off electric and run hot water until gone).
Suburban has 'Push to Reset' buttons in outside compartment (rubber cover above gas valve) Right side is for propane. High temp t-stat has reset button under that cover. If tripped you can feel it reset when pushed.
If that doesn't work.........post more info
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31