I read in a firefighter’s thread that the trick is to use a low pressure spray directly on the battery compartment. (It was a thread about Tesla cars not semis though so that might not apply)
The reason was you can’t actually put the fire out, it’s self oxidizing (it can literally burn underwater) so you basically need to wait till it burns itself out. Fortunately batteries only hold something like 1/10th the energy of gasoline and can’t release that energy as quickly so a fine light spray is enough to keep it from getting hot enough to catch anything else on fire including batteries in the surrounding battery modules.
Takes a long time, like hours to get it to a point they can move the vehicle and literally a couple weeks before the reaction completely fizzles out. They have special lots they tow them to where the car can fizzle itself out without damaging anything surrounding it.
In high school one of my classmates was named Benjamin Dover.
Also had a classmate named Ma Deek.