Resetting an Ideal Halo Zigbee Thermostat

I recently bought a house with an Ideal boiler and a wireless thermostat called a “Halo”. The boiler has a “Halo Smart Interface” fitted into it, which should tell the boiler when to fire. The Halo itself contains the thermostat and communicates with the Smart Interface using Zigbee. During some decorating work the thermostat became disconnected from the boiler. This really confused the boiler, causing it to remain on, burning gas, indefinitely. This is quite concerning and doesn’t give me mu...