A word about chargers. There is no documentation on this. The charging port is center positive (+), and uses a barrel connector that measures 3.45mm outside diameter. So a nominal 3.5mm barrel connector should work fine.

As for charging voltage, use a 5V source. Any 5V USB charging brick will work fine, but it’s best if it provides at least 350mA, since that’s what the phone draws initially. Most brick chargers deliver 1A.

Here’s a look at the connector, and a homemade charging cord.