Use reset button on right side of it. Try it few times. If doesn't works, you have to reinstall firmware at your own risk.
Steps:
1. Download the firmware for your device from here
http
/www.jxd.hk/download.asp?selectclassid=020001
2. Open the upgrade tool, double click "G+MassProductionTool For GP330XX.exe"
3. Click "OPEN", select "burning_firmware_by_usb.conf"
4. Connect the S602 with PC by USB cable, then the charging indicator will lit up
5. Press "Start" and "Power" at the same time. (If it's the first time, there will find USB device at the bottom right corner of the PC)
6. When it displays "Ready! ---àSN:18783a0e0#{53f5", it means the device has been connected with the upgrade tool successfully.
7. Click "Start Download" to upgrade, the status bar will display "complete" when the upgrade is completed.
8. Restart the device, for the first time, it will need calibrate the touch screen.