T4S troubleshooting steps
Please try to reset the headphone: Power on the headphones.Charge the headphones for 10 seconds or so, the headphones would power off on their own(you can see the LED goes out), unplug the cable.Power on the headphones again.And remove the pairing memory of your device,then pair again.
Specifications
Bluetooth version: 4.2
Bluetooth operating range: up to 33 feet (free space)
Bluetooth transmission frequency: 2.4GHz to 2.48GHz
Bluetooth profiles: A2DP, AVRCP, HSP, HFP
Audio resolution: 24bit@48KHz
Drivers: Φ57mm
Impedance: 16Ω
Frequency response: 15Hz-25,000Hz
Sound Pressure Level (SPL): 116dB
Standby time: about 650 hours
Bluetooth music/talk time: about 16 hours
Music/talk time under ANC: 16 hours
Pure ANC time: 16 hours
Charging time: 1.5 hours for full charge
Operating temperature range: -10℃ to 50℃ only
Charging voltage/current: 5V/>500mA
Output power: 25mw+25mw
Headphones dimensions: 188*90*208mm
Package dimensions: 207*240*68mm
Headphones weight: 334g
Package weight: 936g
In the box
T4S headphone
3.5mm turn TYPE-C audio cable
USB TYPE-C charging cable
Flocking bag
User manual
Bluedio T4S Active Noise Cancelling Bluetooth Headphones Over Ear with Mic 57mm Driver Swiveling Wireless Headset Wired and Wireless Headphones for Cell Phone/TV/ PC Gift (Black) - B073DR5ZPQ