The reasons why Sennheiser headphones cannot be charged are as follows
1 Bluetooth headset can not be charged, first of all to find the reason. Usually, the Bluetooth headset battery damage caused. Or the charger is damaged.
2 Check whether the Bluetooth headset charger is intact, and try to use the original charger to charge the Bluetooth headset. Solution: Change the charger or USB charging cable, and try charging the Bluetooth headset.
3 If the charger is good, consider that the Bluetooth headset battery is damaged. You can bring the machine, invoice and wait until the nearby maintenance outlet, test, repair or replace the new battery use.
4 Usually in the use of Bluetooth headphones should pay attention to protect the battery, do not overuse the power, to even charge.