Q: El Capitan install problem

I installed El Capitan on my mid-2010 17 inch MacBook Pro.  On restart it hung up at the Apple logo/progress bar screen with the progress bar stalling at about 80%.

Restarted with Command-R and did Disk First Aid followed by reinstalling El Capitan.  Now the progress bar goes to 100% but then it stays there with the screen displaying the Apple and the apparently complete progress bar.

Please don't tell me to de-install Bitdefender because I can't get to the home screen.

How can I get this back up?

Thank you in advance!