Power does not turn on / power is turning off automatically
Power does not turn on.
When the rechargeable battery has no power remaining, connect the headphones to an AC adapter or computer using the supplied USB cable to charge the battery. link
Power is turning off automatically.
The auto standby function has turned on. In auto standby mode, the headphones automatically turn off after no operations are performed or they are stationary (when they have been placed on a surface such as a desk and are completely motionless) for at least 10 minutes. To turn off auto standby mode, press and hold the volume “-” button and call button together for 1 second or more while auto standby mode is on. link