Power cuts out after 60 seconds - no LCD, no torque

[bikechina]

I have a TSDZ2 on my mountain bike and have been using it trouble free for about 5 months. Now it suddenly stops working within 60 seconds of starting out. The LCD goes blank and motor torques stops. The battery is fully charged. If I disconnect the battery and reconnect, it will work for about 60 seconds before all goes dead. What should I do?

Thanks!