Heatlink is not connecting to Thermostat

[Kinhell]

We had the electricity meter changed today so the power was off for an hour. The Thermostat won't connect to the heatlink with code h71. I've tried pressing the button for 30 seconds a number of times but no joy. There's no lights on the heatlink at all. I've tried Powering off the boiler and back on. The hot water works on the boiler so we know that's working but the heatlink has no lights but has power to it.

[Frustratedddd]

The obvious is power out from a fuse or breaker or adjacent switched spur. you say you have power to L/N, so that rules that out

Could be a faulty H/L, but a little odd if working fine before the job.

One big question I suppose, did the meter person put a test meter on the supply, and now blown the H/L?

The other question, I assume you have correct polarity after the meter change, would be pretty incompetant if they didn't check that, or got it round the wrong way after install???

Did they liven up, then test, and then power of again, then power on again?