At this point, we could try to take the battery out removing the NFC sticker antenna. It will surely destroy the antenna. That is why it is recommended to remove the battery and the NFC antenna together at once. Also because you did not notice the battery ribbon clip that is also hidden under this cover.
Open the eight (8) Phillips screws to remove the plastic cover of the motherboard. I recommend not touching the golden ribbons there. These screws also hold the motherboard. Two screws underneath will secure it, so have no fear at this point. The upper right screw is covered with a Mi logo on new model and it is not easy to access...
Beware! The NFC is glued to the cover. So do not pull the cover forcefully. It will come easily at the next step.