Why is my iPad screen not working after replacing screen and battery?

After I replaced my iPad 5’s screen, battery, and home button assembly, the screen won’t turn on until it is plugged in. Once the screen is on, it is covered in vertical and horizontal colored lines and there is a vertical black strip roughly an inch wide going down the middle of the screen. I’ve already taken the glass screen and the lcd screen off and checked all the connections multiple timed and all of them seem fine. All of the cables are also intact as far as I can tell. I don’t think it’s a problem with the lcd either because the colored lines are fairly uniform and there aren’t any black blotches like I’ve seen in a lot of damaged lcd pictures. Is there anything else I can do?