Google - How to Register chromebook for Device Management
How to force re-enroll if device wiped - https://support.google.com/chrome/a/answer/1375678#reenrollment
Manually enroll chromebook - https://support.google.com/chrome/a/answer/1360534
Chromebook setup steps
Certificate for importing into Google
Step 1 Cert - https://drive.google.com/open?id=13qnIGyv3YdSRpuq2KTdtLl8WM2OxcnDP
Step 2 Cert - https://drive.google.com/open?id=13qUkKqFWM2AITgxws_BUjhVpJe8By_71
If step 2 does not work then use - https://drive.google.com/open?id=1LrNtUn_ccGeW4aezgQdNsSbrUXNavzDe