Removing the battery is absolutely unnecessary. Its very likely the battery would be damaged during the removal… Similar to Slava up above, just lift the freaking motherboard up, disconnect the cables, and install the new display, easy.
I feel like this is the most important piece of information on this entire guide. I drove myself mad disassembling and reassembling multiple iPhone 7/8 Plus devices with this exact issue.
What about the half dozen other steps of removing the back plate, transferring components and reassembling the device?