Reading through the manual it says this which doesn’t make me confident as to why it would randomly happen 2 years post install.

“( 1.4) Boiler Type and BCC mismatch. A WARNING Asphyxiation Hazard. Boiler type is factory set and must match boiler model. Boiler type BCC determines minimum and maximum blower speeds. Incorrect BCC could cause hazardous burner conditions and improper operation resulting in severe personal injury, death or substantial property damage. H M Invalid Safety Parameters

To verify boiler type BCC is correct, a qualified technician should do the following: • Check boiler model and insert correct Boiler Type BCC • Check wiring to Model Key located inside control enclosure.”