Honeywell T6 Thermostat NODE status DEAD: How do I resurrect?

My Honeywell T6 Thermostat has been working well with Home Assistant for months, until today that is.

Now the T6 is unreachable via Home Assistant and the NODE status is reporting as DEAD.

How do I resurrect the NODE?

Try pinging it or power cycle it

Is the thermo working? What does it say for its zwave status?

Did anything in your system change today?

Turns out that there was an issue with the drip pan float switch which tripped the AC Power Loss on the T6 which in turn shutoff z-wave on the T6.

Unfortunately the T6 did/does not send out a AC Power Loss to Home Assistant before z-wave was shutoff.

It should if you have batteries in it. There is a notification it sends to the Power Management Mains Status