Need help! Screen won't turn on!

[PhatboyNYC]

So yesterday my toddler son was playing with my Sprint Diamond. I was watching him when he dropped the phone onto the carpeted ground. The phone probably fell maybe about a foot but I guess the angle it hit the ground caused the battery cover to pop off.

When I picked up the phone, I noticed the screen was off and assumed it was in sleep mode because the battery didn't dislodge or anything. But when I pressed the power button, the phone wouldn't come on. I tried pulling the battery, hard resetting, etc but the screen still won't turn on.

While I was playing around with it, holding down the volume down button, power button and enter button at the same time, I could see the screen come on for a bit, then go blank again.

Physically there's no visible damage, there isn't even a scuff or scratch on the corners where the phone probably hit the ground. However, by some freak chance I think the fall caused something to go wrong internally.

When I pull the battery and restart the phone, it vibrates as if it were powering up. But the screen never comes on.

Considering I don't have insurance on the phone, taking it back to Sprint is not an option. Has this happened to anyone before? Any advice? Thanks in advance.