I finished my training, and scored the required 80% within 3 attempts, but my certificate of completion won’t print.

Whenever you have a login or viewing issue (page not loading, function not working), you may have a browser concern requiring you to clear cache and/or cookies that build up.  Search the Internet for help on these very common topics.
Try: https://help.yahoo.com/kb/SLN4525.html

1. Go to Chrome Menu and then down to Settings.
2. Scroll down and click on “Show advanced settings..”
3. Look under “Privacy”
4. Click “All cookies and site data...”
5. Here you can view the cookies on each site you’ve visited and you can delete specific site cookies by clicking and then clicking x.