Check if the new back cover is seated properly. Screw should go back in provided that its head is not damaged when you removed it. Use the correct screw driver to remove screws.
Green means the charging mode is off and could mean two things, a fully charged battery or a bad logic board. Fans running in full speed is also a result when the battery is removed. How is the health of the battery? Try to download coconut battery to test it. Also, do a SMC reset following the steps on this link.
Hi, try to go to the BIOS settings and check what is the SATA settings. If it is in AHCI try to change it to ATA and vice versa if it is set to ATA and then save the settings before exit. You will have to change the Cache Module to OFF before you can change to ATA.
Hi, I can't really figure out which part you mean as you have not labeled it on the picture. But this picture might help you identify what you are looking for.