Your boiler has sensed that it is getting too hot and has shut itself down as a safety precaution.

Overheat/Limit thermostat or burner thermostat (35e only) fault

What causes this fault?

This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety sensor to cut the power. The most common reasons are a pump failure preventing heat from being moved away from the boiler, or a blockage in the pipework restricting flow. In some cases, the overheat sensor itself may have become faulty and is reporting a high temperature even if the water is cool.