One way of proving it would be to make sure the Power supply links are removed, put a supply on the VL only, then with a multimeter, prove that there is 0 volts on both banks of Servo pin supplies.
Thats if they accept multimeters as evidence…
There is a delay in shipping. I can not gaurantee you would receive them in time. Your local hobby shop could help. Yes that should be sufficient assuming it’s a new NiMH and not an old used NiCad battery from a toy you used to play with 5 years ago. Don’t ask why I’m saying this… For trouble free operation use heavy 18 gauge wires, solder connection, don’t twist the wires. In your case I would recommend a 7.2vdc 1600mAh or better, 2800mAh NiMH pack, and just live with the jittery gripper. 
I use the 7.2V 2700 mAH pack for WALTER. He only has a very few servos, so a single battery is OK in this case. Is still get at least 5 hours or so of runtime.
8-Dale
ok, i got the robot to work with the 7.2 volt battery pack, but when I grip an object too hard, the gripper starts shaking and sounds like the gears are grinding. What is wrong, and how can I fix it?
Use a force sensor to regulate the amount of pressure.
It’s likely you have stripped the gears on the servo. Replacment gears are inexpensive, but it is a hassle. 
Although it’s to late to help you, I will have a force sensing circuit for this exact purpose very soon.