Replacing the logic board problems.

Hey I have an iPad 4 and I replaced the logic board. The old one wasn't working well because the LCD wasn't working after replacing the broken screen. So then I bought a new LCD but that didn't solve the problem. I bought a new logic board for it. And I don't understand why it's still not turning on. My computer recognizes it when it's plugged in. And it also warms up when it's plugged into an outlet. The power button is also broken, but the home button works. Also it is originally a 16 GB wifi iPad but with a 32 GB wifi logic board replacement because 16 GB boards aren't available. PLEASE HELP ASAP!!! Thank you in advance!!