1. Remove the battery.
2. Free phone from any type of plug-in devices (i.e. charger or usb).
3. Push the red END/Power Button and hold for approximately 10 seconds.
4. Plug in charger (ensure charger is connected to electrical outlet).
5. Press the red END/Power Button again for 10 seconds.
6. While charger is still connected, replace battery.
7. Press down on END/Power button until red light goes off.
8. The screen will flash and a small timer icon will appear.
I have a similar problem. Constant "reboot". Tried the procedure above but no luck. Still rebooting. Tried it with the electrical charger and the USB connection.