[gkainz]

tanks verified full by weight?

yeah, indicator should still be green if there's pressure detected on the leg that it's pointing to.

A system reset, sort of, would be
1. Shut off both tanks
2. Remove
3. Verify (by weight) that the tanks are both not empty
4. Reinstall
5. Select a tank to be your primary by pointing your auto selector switch to that tank.
6. SLOWLY (IMPORTANT) turn tank valve on and verify indicator turns green.
7. SLOWLY (again) turn 2nd tank on.
8. Rotate auto selector to second tank. Verify indicator turns green.
9. Reselect 1st tank. That's your primary. When it runs out, autoselector will shift to secondary tank, and indicator with show red. At that point, select 2nd tank.
10. Shut off, remove, refill and reinstall 1st tank.
Lather, Rinse, Repeat

Water Heater continuing to run (burn or just make hot water?) is a mystery. If it just continued to make hot water, I assume electrical element was on? If it burned, then no idea...