Before disassembling your iPhone, discharge the battery below 25%. A charged lithium-ion battery can catch fire and/or explode if accidentally punctured.
Power off your iPhone before beginning disassembly.
Remove the two 3.4 mm Pentalobe screws on either side of the Lightning port.
Opening the display on the 6s Plus separates a thin strip of adhesive around the perimeter of the display. If you prefer to replace the adhesive, have a set of new adhesive strips ready before you continue. It's possible to complete the repair without replacing the adhesive, and you probably won't notice any difference in functionality.
Apply a suction cup to the lower left corner of the display assembly.
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.
Gently grasp the display assembly and lift it up to open the phone, using the clips at the top of the front panel as a hinge.
Open the display to about a 90º angle, and lean it against something to keep it propped up while you're working on the phone.
Don't open the display more than 90º—it is still connected to the top of the phone by the display, digitizer, and front camera cables which can tear easily.
Add a rubber band to keep the display securely in place while you work. This prevents undue strain on the display cables.
In a pinch, you can use an unopened canned beverage to support the display.
Remove two Phillips screws securing the battery connector bracket to the logic board, of the following lengths:
One 2.9 mm screw
One 2.3 mm screw
Throughout this guide, keep careful track of your screws so that each one goes back where it came from during reassembly. Installing a screw in the wrong place can cause permanent damage.
During reassembly, it's critical to place this 3.0 mm screw in the top-right corner of the bracket. Placing it anywhere else may damage the logic board.
Use a plastic opening tool to disconnect the digitizer cable by prying it straight up from its socket on the logic board.
When reconnecting the digitizer cable, do not press the center of the connector. Press one end of the connector, then press the opposite end. Pressing in the center of the connector can bend the component and cause digitizer damage.
Gather the ends of all three adhesive strips in your hand.
Try to keep the strips flat and unwrinkled during this procedure; wrinkled strips will stick together and break instead of pulling out cleanly.
If any of the adhesive strips broke off underneath the battery and could not be retrieved, apply a few drops of high concentration (over 90%) isopropyl alcohol under the edge of the battery in the area of the broken adhesive strip(s).
Wait about one minute for the alcohol solution to weaken the adhesive. Use the flat end of a spudger to gently lift the battery.
Don't try to forcefully lever the battery out. If needed, apply a few more drops of alcohol to further weaken the adhesive. Never deform or puncture the battery with your pry tool.
Do not insert the spudger in the area between the volume down (-) button and the top edge of the battery, or you may damage the volume control cable lying underneath. Do not pry against the logic board or you may damage the phone.
Gently pull the battery adhesive tabs away from the battery, toward the bottom of the iPhone.
To avoid tearing the adhesive strip, be careful not to pull against the battery or lower components.
Pull steadily, maintaining constant tension on the strips as they slip out from between the battery and the rear case. For best results, pull the strips at a 60º angle or less.
The strips will stretch to many times their original length. Continue pulling and re-grab the strips near the battery if necessary.
Hold down the battery with one hand as you pull, or the elastic strips may fling the battery from the phone once they're separated from the rear case.
If the adhesive breaks off underneath the battery and can't be retrieved, refer to the previous step for instructions on how to unstick the battery. See the next step for additional methods.
If you successfully removed all three adhesive strips, move on to the next step. Otherwise, you will need to pry the battery from the rear case.
Prepare an iOpener and apply it to the back of the rear case, directly over the battery. Otherwise, you can apply heat using a heat gun or hair dryer.
Overheating the iPhone may ignite the battery.
Don't try to forcefully lever the battery out. If needed, apply a few more drops of alcohol to further weaken the adhesive. Never deform or puncture the battery with your pry tool.
Do not insert the spudger in the area between the volume down (-) button and the top edge of the battery, or you may damage the volume control cable lying underneath. Do not pry against the logic board or you may damage the phone.
Alternatively, a piece of dental floss may be used to separate the battery from the rear case. A stronger alternative to dental floss is an unwound guitar string, such as a 0.009 E string from a 12-string set.
Thread the floss or string behind the upper battery corners, bring the ends together, wrap them around a folded cloth, and pull evenly.
If your replacement battery came in a plastic sleeve, remove the sleeve before installation by pulling it away from the the ribbon cable.
If there's any alcohol solution remaining in the phone, carefully wipe it off or allow it to air dry before installing your new battery.
Before you adhere the replacement battery, temporarily reconnect the battery connector to the logic board socket. This ensures that the battery is properly aligned in its recess.
Adhere the battery, disconnect it, and continue reassembling your device.
If your new battery doesn’t have adhesive preinstalled, refer to this guide to replace the adhesive strips.
Perform a hard reset after reassembly. This can prevent several issues and simplify troubleshooting.