Disabled peripherals after installing Security Update 2016-005 Yosemite

I installed Security Update 2016-005 Yosemite on my 2011 iMac last night and allowed it to restart. I did not try and log back in until about 12 hours later. I could not get the iMac to wake up using the mouse nor the USB Apple Keyboard. Restarted the machine using the power button, boot up appeared to proceed normally until I reached the user login page. I was unable to input userid/pw with the keyboard and there was no response to mouse inputs.

I unplugged and reconnected the USB keyboard to no effect. The caps lock light will not light up.

For the mouse - I tried changing the batteries and then the mouse altogether, still nothing. Attempting to use the Bluetooth keyboard had similar results - none. I have tested all of the input devices with my MacBook Air and all are working properly.

With no way to make any keyboard inputs, I can't try any of the safe startup or Disk Repair options (yes, I have a time machine backup made before the update.)

Does anyone have any ideas regarding other things to try or should I resign myself to taking it to the local certified repair shop?