Apple iPhone 6 - How to replace the volume button

Remove the two 3.6 mm Pentalobe screws next to the Lightning connector.

Press a suction cup onto the screen, just above the home button.

Be sure the cup is pressed securely onto the screen to get a tight seal.

While holding the iPhone down with one hand, pull up on the suction cup to slightly separate the front panel assembly from the rear case.

Take your time and apply firm, constant force. The display assembly is a much tighter fit than most devices.
Using a plastic opening tool, begin to gently pry the rear case down, away from the display assembly, while continuing to pull up with the suction cup.
There are several clips holding the front panel assembly to the rear case, so you may need to use a combination of the suction cup and plastic opening tool to free the front panel assembly.

Pull the plastic nub to release the vacuum seal on the suction cup.

Remove the suction cup from the display assembly.

Open the iPhone by swinging the home button end of the front panel assembly away from the rear case, using the top of the phone as a hinge.

Several clips along the top edge of the front panel form a partial hinge.
During reassembly, align the clips just below the top edge of the rear case. Then, slide the front panel upward until its top edge is flush with that of the rear case.

Open the display to about a 90 Degree angle, and lean it against something to keep it propped up while you're working on the phone.

In a pinch, an unopened canned beverage works well for this.
Add a rubber band to keep the display securely in place while you work. This prevents undue strain on the display cables.

Remove the following Phillips #00 screws from the battery connector bracket:

One 2.2 mm screw
One 3.2 mm screw

Remove the metal battery connector bracket from the iPhone.

Use a plastic opening tool to gently pry the battery connector up from its socket on the logic board.

Take care to only pry up on the battery connector, and not the socket on the logic board. If you pry up on the logic board socket, you may break the connector entirely.

Remove the following five Phillips screws securing the front panel assembly cable bracket:
Three 1.2 mm screws
One 1.7 mm screw
One 3.1 mm screw

Remove the front panel assembly cable bracket from the logic board.

In the next four steps, take care to pry up only on the cable connectors, and not on their sockets on the logic board.

Use the flat end of a spudger to disconnect the front-facing camera and sensor cable connector.

Use the flat end of a spudger to disconnect the home button cable connector.

Use the flat end of a spudger to disconnect the display data cable connector.

When reassembling your phone, the display data cable may pop off its connector. This can result in white lines or a blank screen when powering your phone back on. If that happens, simply reconnect the cable and power cycle your phone. The best way to power cycle your phone is to disconnect and reconnect the battery connector.

Use the flat end of a spudger to disconnect the digitizer cable connector.

Remove the front panel assembly from the rear case.

Peel back the first battery adhesive tab from the bottom right edge of the battery.
Use your fingers or blunt tweezers, and be extra careful when working near the battery—puncturing a lithium-ion battery can release dangerous chemicals and cause a fire.

Gently pull the battery adhesive tab away from the battery, toward the bottom of the iPhone.

Try not to pull against the battery or the lower components, or you may rip the adhesive strip.
Continue pulling, allowing the strip to slowly slip out from between the battery and the rear case. When you feel increased resistance from the strip, stop pulling and continue with the next step.
If the battery adhesive tabs break off at any point during the removal process, use your fingers or blunt tweezers to retrieve the remaining length of adhesive, and continue pulling.
If either of the adhesive strips breaks off underneath the battery and cannot be retrieved, try to remove the remaining strip, and then proceed .

When you feel increased resistance from the adhesive strip, pull it gently around the lower right corner of the battery.

Continue pulling the adhesive tab upward and away from the right edge of the battery, allowing it to slowly slide out from between the battery and the rear case, until the strip comes free from the iPhone.
Don't allow the adhesive strip to snag on the battery connector, or it may tear or break off.

  Peel back the second battery adhesive tab from the bottom left edge of the battery.

Again, gently pull the battery adhesive tab upward and away from the battery, allowing the adhesive strip to slowly slide out from between the battery and the rear case.
Continue pulling the adhesive tab until you feel increased resistance, and then stop.

When you feel increased resistance from the adhesive strip, pull it gently around the lower left corner of the battery.

Don't allow the adhesive strip to snag on the corner of the battery, or it may tear or break off.
Continue pulling the adhesive tab upward and away from the left edge of the battery, allowing it to slowly slide out from between the battery and the rear case, until the strip comes free from the iPhone.

If any of the adhesive strips broke off and the battery remains stuck to the rear case,  use a hair dryer to heat the rear case directly behind the battery

Flip the iPhone back over and insert a plastic card between the case side of the battery and the rear case.
Do not pry against the logic board or you may damage the phone.
Be careful to keep the card as flat as possible to avoid bending the battery, which may damage it and cause it to release dangerous chemicals.
Press the card in farther to break up the adhesive behind the battery

Remove the battery from the iPhone. When installing the battery, refer to this guide to replace your battery's adhesive strips.

 Remove the following Phillips #00 screws from the upper cable bracket:

One 2.9 mm screw
One 2.2 mm screw

 Remove the upper cable bracket from the iPhone.

 Remove the contact bracket from the iPhone.

 Use the flat end of a spudger to lift the volume control cable connector up off of its socket.

Only pry up on the connector, not the socket on the logic board or you risk permanent damage.

 Remove the following Phillips #00 screws from the volume control cable brackets:

Two 2.3 mm screws
One 1.8 mm scew

 Pull the hold switch and volume control button brackets away from the rear case to allow access to the button covers.

 Begin to peel the volume control button cable up from the rear case starting from the connector end.

Be gentle when peeling the thin portions of the cable up from the case.
Remove the volume control button cable from the rear case.

 Pull the volume control buttons by the metal bar to remove them from the rear case.

The buttons are held to the case with an adhesive gasket, pull carefully to prevent ripping the membrane.