1) Turn off your mobile phone
Before we even start, discharge your iPhone 6 Plus battery below 25%, because a fully charged lithium battery can catch fire or explode if accidentally punctured.
Turn off your phone completely to avoid damaging it during the repair. Press the Sleep/Wake button for about three seconds until the slider labeled "power off" appears. Swipe it from left to right, and it's turned off.
2) Remove enclosure screws
3) Lift the display
To lift the glass you will require an attractions cup, a hard plastic pick, and a heat gun(a hairdryer will likewise work), which you get in the pack aside from the heat gun. The screen is glued to the frame, use a heat gun to heat the outer edges of the display to about 60°C (140°F). You can do it without the heat gun but it's easier with it.
You can do it without the warmth weapon yet it's simpler with it.
Place the suction cup over the Home button or next to it. While lifting the screen with it, insert hard plastic pick between the aluminum frame and the display. Press down the aluminum frame and slide the pick all around the iPhone between the aluminum frame and the display frame. Try not to stick the pick in too far because that could damage the flexible flat display cables.
Use the pick to push the display so the tabs come out of the aluminum frame. 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.
4) Remove battery bracket
Remove two Philips screws from the battery connector bracket (Red one is 2.3mm screw and yellow is 3.1mm screw).
5) Disconnect battery connector
Use a tip of your finger to pry up the battery connector from its socket.
6) Remove the front panel bracket
Use an Philips screwdriver to remove 5 screws securing the bracket. Then simply remove it.
7) Disconnect all the cables under the front cable bracket
Use a tip of a finger or a flat spudger to pry up and release following cable connectors: Camera and Earpiece speaker, Home Button, Data Cable, Digitizer. Then simply remove the whole front assembly.
8) Unscrew home button
Unscrew the two 1.8mm Philips screws securing the home button bracket. Then carefully remove the home button bracket from the front panel. After removing metal covering, use the plastic spudger to disconnect the home button cable connector by pushing it up and away from the home button.
9) Remove home button
Apply low heat to the home button to soften the adhesive securing its membrane. When its soften enough, use your fingertip constant pressure on the home button from the front side of the display assembly, until the membrane separates from the panel. When you get it out, use the point of a spudger to separate the home button cable from the adhesive securing it to the front panel.
10) Reassemble everything with the new screen
Your iPhone is completely disassembled. Now take your new screen and reassemble your phone by following this guide in reverse order, and then test everything up to make sure you did everything properly.
Test everything up
Congratulations, you changed your iPhone 6 Plus screen all by yourself. Now just test a few things to make sure everything is working properly:
-Test the brightness of the display.
-Test the touchscreen, select an app, and drag it all around the display. If it is following your finger everything is fine.