I replaced my battery, and now the screen doesn't work.

So I've been screwing around on a bunch of different sites now and have not been able to pinpoint my issue. I purchased a phone off ebay which worked fine but the phone would die once the battery was around 78-82% and sometimes higher when using certain apps like the camera. I tried everything I could software-wise, because it appeared other people were having similar problems, it solved the camera issue but within a week the battery was pretty much useless, so I contacted the seller who sent me a new battery.

I've replaced batteries and screens in Iphones a couple times before so it should have been a pretty routine process. It appeared to go fine, I plugged it back into my laptop and itunes recognized it and loaded it fine, but the screen stays completely black. I tried powering it down manually with the home and power buttons accidentally triggering the voice command which I tried and it worked fine. I then noticed the vibration also does not work now, so I really couldn't tell for sure if the phone had powered off or not to check the connections.

So I had Itunes open and held the home and power as soon as it didn't see the phone anymore I released the buttons and unplugged it as quickly as possible. I checked all the connections twice and they're all fine, still no vibration and a black screen.

I couldn't find any posts with anyone having these exact same issues. I'm not sure why the screen would stop working after being fine a couple days ago last time it was on, and I don't know why the vibration doesn't work as well. I have an old screen that's cracked to oblivion and basically unusable that I could try plugging in for the heck of it if that would help.

Thanks in advance for anyone that can offer help.

Update: I put my wrecked screen in and I at least get fraction of a second blips of light. I could just place the glass from the other screen onto this one if I could get it to work.