Put it on a 2 amp charge for a day.
The vehicle in question probably has a ~75 amp hour battery.
10.5 volts is considered 100% discharged. If the battery in question were still healthy, at still near full capacity when it was drain to 9v, it would require anywhere from 110 to 125% the energy removed from it. Lets say 125%
94 amp hours 94 amp hours divided by 2 amps is 47 hours.
If the charger used does not recognize the battery because of the 9v factor, the battery should be paralleled to a known good battery and then charged until its resting voltage is high enough that the charger will recognize it..
Since the battery in question is likely has nowhere near full capacity remaining, a day at 2 amps might be enough to bring it near full charge.
If this theoretical 2 amp charger does not raise the voltage into the mid 14's it is likely it will never