Which operating system you are using ?
Firstly charge your battery sufficiently and then remove your charger cable.
Once done see if your PC is coming out of sleep mode by closing its lid. If this doesn't work then you will need to do hard reset as I believe its battery can not be removed you need to try and press power button for around 15 sec to turn it off.
Try this and let me know if it works.
Remove your charger and then press power button for 15 second. It should shut down your machine.After restart it should work as expected.
Please see if this works !
By hard reset I mean try and remove your battery. But I think in your machine battery can't be removed.If you can remove it please remove it and attach it again.
Please try following :-
Turn off the computer.
Disconnect all peripheral devices and remove all USB devices and media cards.
Disconnect the AC power adapter. If the Chromebook features a removable battery, remove the battery.
Press and hold the power button for at least 7 seconds.
Reconnect the AC power adapter.
If you removed the battery, do not reconnect it at this time.
Turn on the computer.
If above method doesn't work then we can fix it by doing chromebook recovery.Recovering your Chromebook lets you remove and reinstall the Chrome operating system (OS). While recovery can resolve most serious issues, it will also permanently erase all information on your Chromebook's hard drive.
For that you should try following :-
To recover your Chromebook: