Ok. Good as any place to start. I am spoiled by the all-in-one systems, I guess, otherwise I would not have been so carelessly running it dead.You probably shouldn't have ran the batteries to 0%. That's bad for any battery. The solar charge controller may not know what to do with a battery that depleted. Connecting a regular power supply may be one way to resurrect the battery. Once you get the battery to something like 20% the solar charge controller may be able to take over. Depending on the BMS, you may have to bypass it.