Put a box or a stack of books to the right of the controller so you can prop up the midframe while disconnecting its ribbon cable.

Secure the back cover with one hand, and use your other hand to grip the midframe's left edge.

Lift the midframe and rotate it over the right edge of the back cover, so the midframe's right edge is on your workspace.

Prop the midframe up, being careful not to strain the ribbon cable.