Cracked Screen and No Power

My son dropped two kindles. One the screen is cracked and won't turn on at all. The other, the screen is pretty much shattered, but works fine.

So, on the shattered but works, should be a straightforward screen replacment, where do you recommend getting a replacement screen and what is the average cost?

Where do I start with the one that won't come on at all? Obviously, I do need a replacment screen, but beyond that, what would keep it from coming on at all? Is it worth fixing?