Opening the iPhone's display will compromise its waterproof seals. Have replacement seals ready before you proceed past this step, or take care to avoid liquid exposure if you reassemble your iPhone without replacing the seals.
If using a single suction handle, apply it to the bottom edge of the phone, while avoiding the curved portion of the glass.
If your display is badly cracked, covering it with a layer of clear packing tape may allow the suction cup to adhere. Alternatively, very strong tape may be used instead of the suction cup. If all else fails, you can superglue the suction cup to the broken screen.
Pull up on the suction cup with firm, constant pressure to create a slight gap between the front panel and rear case.
Insert an opening pick into the gap.
The watertight adhesive holding the display in place is very strong; creating this initial gap takes a significant amount of force. If you're having a hard time opening a gap, apply more heat, and gently rock the screen up and down to weaken the adhesive until you create enough of a gap to insert your tool.
Open the iPhone by swinging the display up from the left side, like the back cover of a book.
Don't try to fully separate the display yet, as several fragile ribbon cables still connect it to the iPhone's logic board.
As pictured, make sure the frame comes off with display and doesn't get stuck in the device.
Lean the display against something to keep it propped up while you're working on the phone.
During reassembly, lay the display in position, align the clips along the top edge, and carefully press the top edge into place before snapping the rest of the display down. If it doesn't click easily into place, check the condition of the clips around the perimeter of the display and make sure they aren't bent.
The bracket may be lightly adhered in place. Lift gently but firmly to separate it.
During reassembly, this is a good point to power on your iPhone and test all functions before you seal the display in place. Be sure to power your iPhone back down completely before you continue working.
Use the point of a spudger or a fingernail to disconnect the OLED panel cable connector.
To re-attach press connectors like this one, carefully align and press down on one side until it clicks into place, then repeat on the other side. Do not press down on the middle. If the connector is misaligned, the pins can bend, causing permanent damage.
Use the point of a spudger to pry the digitizer cable connector up from its socket.
This connector's recessed location makes it tricky to reconnect. Take your time and align it carefully, then gently press it into place with your fingertip—first one side, then the other. You should feel it click into place.
If any part of your screen doesn't respond to touch after your repair, disconnect the battery and then re-seat this connector, making sure it clicks fully into place and that there's no dust or other obstruction in the socket.
If you successfully removed the entire ambient light sensor, as shown in the first photo, continue to the next step below.
If the white diffuser strip detached and remains embedded in the display, as shown in the second photo, you will need to carefully lever it out along the top edge using a thin blade or pry tool. Re-applying heat first may make this task a bit easier.
During reassembly, install the diffuser into the display first, making sure it faces the right direction (the front-facing side is shown in the first image, and the rear-facing side is shown in the third).
Then, set the ambient light sensor on top of the diffuser. You will need to hold the sensor in position while installing the screws securing the earpiece/sensor assembly. Once the screws are tightened, the sensor will stay in place and work normally.