Help translating instructions since English website has been shut down
Two options:


Press the power button for more than three seconds. This is what instruction says: 电源开关长按3秒以上开机.
According to this Belorussian guy, you can take a needle and press the reset button inside the round hole near the SD card slot. (This method is not on the manual.)


These methods might not do an actual hardware reset, though. No guarantees here.