Water heater

Modern LP thanks have an Excess Flow Feature. LIkely when you first reconnected the tanks you opened the valves too fast and tripped it.
Open till you hear gas flow pause and continue from there SLOWLY after 1 minute till full open works best.

Everything is OK. Fiddled with the connections to make sure no corrosion and disconnected the LP tanks, reconnected LP tanks and flipped the switch and it lit off.

If you run out of gas it will try to relight (Assuming it runs out when lit) and if it fails it will try again, and if it fails it will try again, then it will shut down, lock out and fire up ye old FAULT (or Check) light.

Turn off. count to 1 turn back on. Should be good to heat. (NO guarantees)
In some cases. especially trailers you may get some air in the line. if this happens the heater should Try, fail, Try and succeed but if the lines are long and big enough there is a possibility it may go into fault one time.

Finally when you open the tank valve after refilling. Opening too fast can cause a safety device to engage and limit gas flow below the heater's need.

When the WH ran the LP empty, the Ignitor tried for 3 attempts and then shut OFF. You did not destroy the Circuit board by running out of LP. Did the WH have water in its tank when it stayed running? Doug

As long as there was water in the tank, I don't think there would have been any problem?

If the pilot blew out during travel, the igniter would have just tried to light after about a dozen tries and then the solenoid should have shut off the gas and then you should see a check light for the WH.

The gas 'should' not have kept flowing with no flame... If it did, then you have more problems with the system..

Since gas does not seem to work now, I can't really say? There are a fuse or 2 in the WH compartment itself?

Dunno... But, good luck with it! Mitch