Hi @bamboo ,
To replace the battery you need to remove the LCD screen, as the battery is mounted on the back of the mid frame which is screwed into the back cover from the front.
Here’s a [https://www.youtube.com/watch?v=O0kyhwz45Xs|video] that shows the teardown of the phone.
From about 2:30 minutes onwards in the video (after the screen has been removed), you will see how to get to the battery.