Won't power on, replaced DC-in, topcase, RAM, etc.

Hello! I've got a 2.4GHZ white MacBook which will not power on. Absolutely nothing happens when you try. I've replaced the DC-in, topcase, RAM (I tested both slots) and AC with known-good parts. The DC-in shows a solid green light, but there is no other sign of life. I've tried resetting PMU/PRAM, but it doesn't even do enough for that to matter.

To me, this means the board is dead, and this is where my abilities drop off and I pretty much give up. It's not under warranty, and it does not appear to have water damage. My question is, can anyone think of additional troubleshooting steps to take? If not, are there entry-level logic board repair steps that I could pursue? People buy dead machines like this all day from me on eBay, so I know there must be ways to repair dead boards. If anyone has ideas, I'd appreciate it.

Thanks!