At this point it's a good idea to test your repair, in order to make sure your iMac works properly before you seal it back up. Follow the next three steps to temporarily reconnect the display cables and boot up your iMac prior to pulling the protective film off the adhesive strips.

Gently insert the display data connector into its socket on the logic board. Be sure to press it straight into the socket, and insert it completely.

Flip the display data connector lock down onto the socket.

Insert the display power connector into its socket on the logic board.