Using a Phillips Head #1 screwdriver, unscrew the 15 screws on the bottom of the device
After all the screws are unscrewed, remove the bottom plate. If this is the first time that you are removing this back cover, the last screw is hidden under the "factory seal" label. You will need to break that label to reach that screw.
Keep track of all the screws and which slot they came from, as they slightly differ. We recommend this system: lay out on a piece of paper and pretending the paper is the device. Place the screws on the paper approximately where they would go.
Another method for keeping track of all the screws would be to secure each removed screw near the hole that it was removed from with a piece of painters or masking tape. This type of tape is easy to remove from the fuzzy surface but strong enough to secure the screw to the back cover.
Wedge the spudger underneath the battery, and apply pressure to lift it away from the rest of the device.
Gently pull and wiggle the multiple colored wired connector out from the socket.
If you are removing the original battery, the back has a couple foam strips that were installed for cushioning. Those can be carefully removed and placed on the new replacement battery, but it is not necessary.