Chosen Solution

I replaced my ipad air 2 a1566 screen. I’m testing before sealing and only getting apple logo and red screen and reboot. Anyone have a step by step on how to fix this?

Sounds like a logic board issue, it’s quite likely it got damaged when the screen was broken or possibly during replacement. Since it’s not a simple part replacement you won’t find any step by step guide on this fault, you’ll need to find someone into microsoldering who’s got skills and tools for proper troubleshooting.