Or the battery/starter cables. What voltage do you get at the battery?That didn't work. Maybe it actually is the battery. Jumping it has helped before.
Do you have a set of jumper cables (for car-car jump starting)? If you can connect one clamp to the large post on the starter where the cable from the battery connects then connect to other end to the battery + (in that order!). Then run a smaller jumper (as per previous) from battery + to the male contact on the gray wire and see if it cranks. As always be certain you are in PARK with E brake on.