Water heater

When you turn on the W/H switch inside, The DSI Fault light should light. Then you should hear a series of clicks (not very loud) That is the igniter trying to light the gas. If it lights, the DSI Fault will shut off. If it doesn't light, It will make 3 attempts to light. If all 3 fail, it will no longer attempt to light. If you go outside and open the panel, and have someone turn it on, see if you smell propane. Don't get your face to close incase it lights and "swooooosh" no eyebrows. If you smell gas, and theres no flame, it's probably the igniter needs changing. I've heard some say they lit it with a match, but I never have. 

nothing tripped

Kingbro, after checking the water heater manual the 12 V.D.C. T-Stat Hi-limit might have tripped and be causing what you are experiencing.  This is a High limit water temperature cut off and if that sensor is tripped you can manually reset it behind the outside door in the upper left corner just to the left of the pressure relief valve you will see two black reset buttons the left one is for the 110 system and the right one is for the gas system.  If the water temperature got above 180* it should trip both systems and to reset these sensors the water temperature in the tank has to be below 110* then you can push the buttons in to reset both of them or either one.  You might want to try resetting them first.

I found on my 190 that all the wires going to the water heater control box from the switch panel had bad connections.