Unable to boot to external DVD after removing Super Drive from late 2011 Mac Book Pro

I removed my Superdrive and replaced it with a 750 gig hard drive. I tried to install Windows on a bootcamp partion on my primary hard drive and found that it would not reboot to external drive during installation. Sierra reads the external dvd when using this dvd drive to install programs that don't require a reboot like Office for Mac 2011.that install was perfect.
Since I am retired and have lots of time on my hands, I removed the new hard drive and adapter and reinstalled my Super Drive. Windows installation went perfectly. No problems at all.

Bottom line is that if you plan to install Windows on a late 2011 Mac Book Pro,do it before you replace the Superdrive with a hard drive. I am no computer expert but it seems to look at whatever is attached to the internal Optical cable first during reboot and if it isn't a superdrive, it will go no further..will get message saying Boot Manager not found..

To do that you need to pop the superdrive back in as you found out.

Par for the course on any Mac that has had the superdrive removed or has a failed superdrive.