Ninebot ESX Error Code 45
"built in battery is overly discharged and not available to charge. Please replace battery. (45)"
Cause
Error 45 on a Ninebot ESX scooter is related to issues with the internal battery being "overly discharged".
This is similar to Error 19, but Error 45 and Error 46 are solvable.
Error 45 occurs when the internal batteries are left for too long or somehow end up discharging lower than the BMS should normally allow for.
Fix
Plug the battery into the controller, and plug the controller into the charger.
If the charger oscillates between the red charging light and the green finished light, leave it for a few hours.
It will likely do this a number of times before the voltage is high enough for the charger to stay on.
Clicking on and off from the charger is normal during this process.
If the battery does not even attempt to charge, plug an external battery that is partially charged into the controller and plug that battery into the charger.
Similar to before, wait for the charger to stop clicking and start charging on its own.