Overheating steam boiler (S1 Armonia - Old)

[MIOss]

Hello Everyone,

I find myself in quite a predicament. My S1 Armonia's steam boiler kept "blowing up" (via the overpressure safety valve).

Background:

I've beed trying to adjust group temp while the machine was on and sadly I've dropped the cover on top of the steam boiler. The cover hit electrical connectors on top of the boiler and blew the fuse in the wall (machine fuse on the main board is fine). After resetting the breaker my machine turned on fine, everything seemed to be working, till the boiler safety valve blew.

I've diagnosed the issue but I'm not sure what is causing it and how to fix it.

Steam boiler blows since the heating element is constantly supplied with current. Toggling either of the on/off switches to the off position doesn't affect that (the heating element is getting power in all three scenarios - the main switch is on and the boiler switch is off, mains switch is turned off without switching off the boiler button and when both of them are turned off). Both buttons seem to be working just fine in other areas - steam boiler button still turns off probes and the pump for the boiler, main switch still turns off the group heads (heating , pumps, lights, all that). For all intents and purposes machine works just fine - if I unplug the contacts from the heating element.

I've checked the machnie with a meter and the circuit feeding power to the heating element is always complete o matter what I do with the switches. There's no current bleed to the ground wires or the frame, everything else looks fine, I've also checked the cables going from the control unit to the heating element and they are fine as well, no shorts or anything fishy. Control unit motherboard looks okay as well, all circuits on it are complete (meter) and nothing looks visually blown or otherwise damaged.

Does anyone have any ideas as what might be going on here?