If you really want to get things redone like originally done we can also discuss or point out the hardware that was dyed "safety" red
As Pete mentioned its a fairly easy process to install. Lifting the large somewhat heavy and hard to handle fold down section into the car to start is likely the most difficult and brings with it the greatest chance of hitting something you done want to.
- It is bolted (loosely) into place and see if you need any spacer plates between the hinge and the floor mount.
- Then align/space the fold down section between the quarter panel trim panels and slight it fore and aft to get the L shaped section positioned correctly in place with the front surface of the quarter panel trim.
- Tighten the fold down section down. Then test the fit with the fold down section in the up right position. IF its attached at an angle the gap between the drivers and passenger side may be too tight or too loose and the fold down is installed crooked/at a slight angle.
- Insert the rear flat panel (with the trap door open) and even it out between the back edge of the fold down, rear corner pieces and the trap door opening. If its a good fit attach it in place
- Check the fold down to rear floor panel bumper adjustments to center the locks to the fold down latch holes
- Check the trap door and adjust striker on the carpeted back edge if needed
Think that is about it. As you've seen there are allot of parts and one being off can create issues and need for further adjustment