Take the keyboard again, being careful to not tilt or reverse it or else the small rubber bells would fall. Put the keyboard in the same position of the beginning, check that the rubber bells of the keys are all in place.
Put the shielded circuit in its original place, check the alignment of the contacts first.
Put the bottom cover in its place, check that the keyboard wire is in its right place.
Insert the screws of the circuit board first and tighten them.
Insert all the other screws and turn them.
The shielded keyboard is ready.