Nest thermostat suddenly stopped working

[SeLHopeful2024]

Hoping someone can help please.

Nest thermostat (came with the house we've just bought, so limited experience or knowledge of its setup etc) has suddenly stopped working.

It appears it is no longer holding charge and we have lost all controls.

Google support haven't really helped as yet, and now I've had to leave the issue unresolved as I've gone away for a few days.

The error is H72 and at times also E4 which suggested the Rh wire was an issue.
The thermostat is plugged into the wall and we assume the plug is attached to a socket in the garage. This socket is working for other electrical and we changed the fuse in the plug just in case.

It looks like I can buy a replacement thermostat, but at nearly £200 I don't want to buy that if there's an issue in the wall wires.
No idea why there would suddenly be an issue- nothing has changed, no power outtage etc.

Thanks for any suggestions.

You need an electrician to come and check the wiring if you’re unable to google the E4 code and look at the trouble shooting.

Mine did this last week - totally lost power due to the furnace not sending power to it via the RH wire (that's where it gets power from). Pull the front off the nest and check the RH wire isn't loose first.

for ours, the furnace kill switch had flipped, it's a bit over sensitive.

it might be a plumber you need if it's the central heating rather than the nest itself

Thanks. I just don't get how the wiring can suddenly play up when it's not even been touched.

Looks like another call out...blooming house moves!
You just never know what will throw itself onto the priority list next.