I'm not an expert on starter motors, but I have that they can have bad spots. That could help explain your warm start issue. If the spot was not too big it might not start at first but when you stop cranking it, maybe it came to rest in a position that would work the second time. Now that spot might be too big for you to actually get it to turn over. I would still try to get the car started with Jumper cables hooked up, if that doesn't work then someone with troubleshooting tools will have to take over.
By the way, I think you can get a cheap DMM from radio shack for about $20, might be worth it for the future.