New Motherboard still not powering on, ideas?

Replaced the motherboard on a MacBook a1286, because the MacBook wouldn’t power on. I’ve done all of the resets a few times and it’s still not powering on. Now, when you attempt to power on the fans will start to spin and the hard drive does make some noise as if it’ll start, but the computer will not stay on. Has anyone seen this? I’ve also tried a new I/O board as well.