Put on a heatproof glove to avoid burning your fingers.

With a very thin spudger like the one shown gently pry the back cover away from the phone about half way down the long edge of the cover on either side.

Be aware that the glass may crack. If it does take care to avoid cuts and splinters and fit a new rear cover when reassembling the phone.

When you have enough room, insert some plastic cards (such as plastic playing cards) and use them to cut through the glue around the bottom half of the rear cover.

The battery is stuck to the rear cover with double sided tape. Separate the battery from the rear cover without lifting the battery up at the top end, or you may damage the battery flex.

Be careful not to pry around the top edge. If the patch antennas are damaged when the cover is removed be sure to replace them with new ones.

Slowly lift away the back cover, detaching the top edge last.