Hey there, I'm Tim and will be helping you.
Chromebooks occasionally have a problem where they get hung like this, you need to pull the power plug, force it off and remove the battery if you can - Some require dis-assembly, some do not. If you can, remove the battery and , wait a few seconds, put it back in, connect power and boot. If the battery is hard to get to, simply leave it running while not plugged in to in-dose a full power cycle - That should clear your issue. Let me know if you need further assistance.