1) Unplug the Chromebook
2) Perform a hard reset by holding down the power and refresh keys for 10 seconds.
3) Then check to see if the charging indicator light turns on when you plug in the charger. If not, try another hard reset and check back.
4) If successful, charge for 1 hour before turning on the Chromebook.
This video also shows the above instructions - https://www.youtube.com/watch?v=pqUAGl-P7hM