I have a 2017 Harley Breakout with key-less start and alarm with siren.

Was riding and engine light came on but bike ran normally and arrived at destination so turned the bike off. Next time I tried to start the bike, it was like the alarm FOB was not present and the siren went off. I mucked around for so long the siren battery went flat. I went to look up the alarm over-ride instruction which I found.

Came back to the bike but now the dash is dead (it wasn't dead before) so I can’t enter the pin. Battery voltage is normal and fuses checked good.

Have left if hooked up to a charger but the alarm back-up battery fails to recharge.

If I lift the bike off the side stand the blinker flash with no siren, Even with FOB present.

If I pull the fuses out, nothing happens, normally the alarm would go off as the FOB is not present, this is now not the case.

The only evidence the spedo is not dead is the alarm red light is flashing, nothing else ever works.

My initial thoughts were the ECU, BCM or something to do with the immobilizer.

Any help would be appreciated.

Yes. The FOB battery is GOOD.

The alarm's 9 volt battery was good but is now FLAT because of me mucking around with this defect.

Bikes main battery is GOOD.

"I think" as the bikes main battery is good, the bike should still start normally and the alarms 9 volt battery should charge once the bike is ridden.

The only code was "LOST COMMUNICATION WITH BCM" U0142.

Erased code.

Started bike and all is normal. Even the alarm and alarm backup battery is working normally. Unbelievable