Communication Breakdown

How do you explain to a child with the motor skills of a 15 month old and the language skills of an 8 month old the meaning of the word no? I think it's a really bad idea for Noah to push his ride on toy over to the fireplace so that he can climb on top of the mantle and jump off. I also would prefer that his rocking chair not be used as a ladder to help him scale the bookcase so he can see if his drumstick is strong enough to break the glass in front of our African sand art. But he doesn't understand the word no. He interprets being removed from the situation to mean "Try again, and this time see if you can jump off before Mommy crosses the room." I know that toddlers aren't exactly cooperative when it comes to obeying the rules or being safe, but it's frustrated to know that he just doesn't "get" the rules. A few weeks ago all of Noah's batteried toys decided to die on the same day. Noah was clearly frustrated (evidenced by screaming fits on the floor), but I had no way to explain that the batteries died and we have no more and Daddy will get some after work. He just spent the day trying to get broken toys to work and crying when they didn't and it broke my heart. I want him to understand, but I know that it's going to take lots of time and therapy before that happens. Hopefully we won't kill each other between now and then.