This was the hardest part for me because I didn't flip the frame.

Turn the frame upside down so the top is now the bottom.

Insert 4x M5 T-nuts into the frame channel and slide them so you can thread 4x M5x8 button head screws into them. Again tighten the screws snug than loosen 1/4 turn.

Turn the frame over and tighten the 2x M6 button head screws than the 6x M5x8 button head screws to secure the top plate to the frame.

Tighten the 4 stepper mounting bolts. Do not forget about the M3x10

Tighten the M3 screws for the bearings. 1 on top and 2 on the bottom of the assembly.

Tighten the 2x M3 screws for the standoff spacers

Tighten the 4x M5x8 button head screws on the bottom plate