Since you just finished looking at the back if you just peak around the corner near the top and just barely visible are two buttons designed to blend in.
This is all that exists in terms of a control panel for the HD91.
The first one (closer to the back, is power, and just forward is a source select, with in indicator light in between.
There are no navigation controls on the HD91 hardware, no access to menus, etc. In other words, do not lose that remote control, unless of course you've tied the HD91 projector into a larger room or home control system. Without the remote, or room control, there's no way to change color modes, adjust features like Brightness, or Dynamic Black, etc.
The power switch has it’s own indicator light on it, which you can just make out in the image. With the projector powered up, the indicator is blue, as shown here. It's Red when the projector is off, and blinks during power up.
Control panel consists of a power switch, source selection and two indicator lights. Don't lose that remote control!