After installing SSD in 2009 iMac I only see a black screen The computer chimes, and when I press any key like the option or R keys to enter recovery or the Startup Disk Manager, nothing happens. I tried to reset the SMC to no avail. 

I have a 3TB portable HDD with a bootable install partition of Sierra I would like to install on the SSD.
Fixed it. The DisplayPort connector came undone.