the dvice is not working after full charging

[amirc88]

I have an urgent problem I have M8 device and yesterday I charged him all night, I woke up this morning I saw the device is on 100 percent battery but will not turn on, at first he still showed that he responds by shown in battery mode (100%). Now he did not show it either . I tried the charger is connected to press the shutdown and then half volume up and down at the same time but it does not work
thanks for your help :-(