unresponsive green charging light on but not plugged in

[Ceam]

My daughter's Sony Xperia Z3 phone is fully charged. She unplugged it but green light stayed on and phone is unresponsive. Screen is black. Any suggestions please

[Samuel1 · Accepted solution]

Try pressing on/off button and volume up-button simultaneously, this should force restart the phone.

[Curnow1]

Try pressing Power botton + Volume up key. This should shut down the device stright away. Then power it on. 

[Ceam]

Thank you