Thanks for fuse info on Avia. Fuse on heater was good. Is this the fuse you are referencing? No green power light on ALDE panel on/off button yet. suspect another bad fuse or main PCB on boiler bad. (installed another after I dropped one so how to retrieve them so they don't short out main PCB HA! Magnet?) . How to get fuses out suggestions needed. All other D.C, fuses checked O.K. Sourcing for battery backup for ALDE monitor system next.