A Chromebook that is not powering on or charging may require a hard reset.

This is a simple procedure that can be done in about a minute.

With Chromebook plugged into the AC adapter

1. Turn off your Chromebook. (Press and hold the power button until the power button light turns off.)
2. Press and hold Refresh   +  Power   for 30 seconds
3. When your Chromebook starts up, release Refresh .

The refresh key is located over the 4 key on most Chromebooks

If that does not resolve the issue, remove the AC adapter, and try again, lastly attaching the AC adapter and trying a final time, close the lid and re-open

Original article https://support.google.com/chromebook/answer/3227606?hl=en