Microsoft Lumia 640 LTE Single Sim - Manual (Page 6)

Replace the battery and back cover
1. Line up the battery contacts, and put the battery
in.
2. Press the bottom edge of the back cover against
the bottom edge of your phone, and snap the cover
into place.
Charge the battery
Plug a compatible charger into a wall outlet, and
connect the micro-USB end to your phone. You can
also charge your phone from a computer with a USB
cable.
If the battery is completely discharged, it may take
up to 20 minutes before the charging indicator is
displayed.