First did you properly shut your system down Vs put it into sleep mode? If not the act of disconnecting the battery or SSD could corrupt or damage the SSD.
Did you use proper ESD practices? Depending on where you are the dryness in the air raises the risk of static discharge. Even inside with air conditioning the risk of static can be present. Before you open your system you must think how to remove the risk of ESD.
Did you disconnect the battery and did you use a non-metal tool to pry off the SSD ribbon connector (Step 10)? If the answer is No for both you could have damaged the SSD.
Otherwise it sounds like you damaged the ribbon cable or the contact block on the logic board. (Step 10).
Did you setup a recovery USB Thumb drive, CD/DVD or have an external HD which has a bootable system? Try using one of these to boot your system up and then use Apples Disk Utility to repair the disk. If it is unable to repair you may need to delete the partition and rebuild things (hopefully you made a backup).
If that doesn't work you'll need to either replace the ribbon cable and/or the SSD, assuming you didn't damage the logic board.