Suburban uses 2 different sets of t-stats.....one set for 120V AC element and one set 12V DC for propane
If the normal t-stat fails to OPEN at preset temp (130*F) then the HI temp one is preset to 'trip' OPEN (170*F)
When it trips it has to be 'reset'
In outside compartment left side is a rubber cover with 'Push to Reset'
Left button is for electric element.
Push it and see if it resets. If it does electric element should get power again.
BUT you will need to replace that set of t-stats cause normal is not opening and water will heat to 170*F then trip HI temp t-stat again.
IF it's not a tripped t-stat then it could be:
Loose connections, faulty element, tripped 120V CB