It seems to me that something is breaking the circuit causing the EHC to cycle On and Off when you try to start your bike. The EHC is grounded via the key switch when turned on to turn the EHC ON. Since, it is unlikely that the Circuit is being interrupted, then trying to start is causing the voltage to the EHC to go out of it’s normal band. If it’s not the battery voltage dropping out of range rapidly, I would believe it’s the EHC especially since you said the slam button works.
These are my thoughts but not being familiar with this type of failure, I hope someone else can chime in to help you out. Also, you could get your EHC tested.
These are my thoughts but not being familiar with this type of failure, I hope someone else can chime in to help you out. Also, you could get your EHC tested.