Your boiler appears to have no power reaching it, which is likely caused by an external electrical issue or a blown fuse inside the unit.

Fault with mains supply or PCB fuse.

What causes this fault?

This fault occurs when the electrical circuit feeding the boiler is broken, meaning the unit cannot receive the power it needs to operate. The most common reason is a blown fuse within the boiler's internal control board or an issue with the external power switch on the wall. In some cases, a power surge or a failing internal component can cause the fuse to pop as a safety precaution to protect the sensitive electronics.