IMA/emissions Error - unable to scan with OBDII adapter

Hi, my vehicle runs and drives fine with some issues: remote keyless entry and power lock switches no longer work. I have resorted to turning off the ignition in gear to keep all the doors locked when parking because the doors all unlock if I don't, so I'd have to manually lock them all otherwise. The check IMA and check Emissions System lights come on in the dash display; there is no power to the stereo system, there does not seem to be any operationality of the traction battery and the meter on the display shows it as continuously depleted without the animation that usually shows up when the battery is charging or discharging with normal functionality. The climate controls and lighting all work fine. My OBDII adapter works fine (draws power and connects) in my other vehicle, but is not getting power in this one, engine on or off. I've checked all the fuses that I think could be causing the problem and they all seem good. I don't own a grid charger but have seen a number of forum posts indicating that an overnight charge on a grid charger might solve the problem. Any thoughts on what other diagnostics I can run on the car before resorting to a battery pack rebuild/replacement? Thanks!