Locate the four screws holding the battery in place. They are marked with M2 and arrows. Unscrew them all.

The connection between the battery and the mainboard is easily disconnected by pulling the plug while wiggling a little left and right with your fingernails or a spudger.

Do not pull on the cables but the plastic connector to avoid damages to the cord.

Lift out the battery and replace it with the new one. You're finished!