I brought a 2004 back to life. It had not run in 10+ years. So I bought it knowing nothing about it, I threw some new batterys and it fired right up. But it has a Beep that will not go away unless you throw the main breaker and cut off all the power.
It’s a low volume version on the Ebrake warning buzzer. Like I said only thing that kills the Beep is killing the power.
The only other clue I can offer is the stock Delta Q is in fault mode. Red Flashing light. (Like the charger is broken)