First, try training your RG; this will help the whole system come back faster after a power outage.

Koolkid has a great Interative RG Trainer here.

When you press OK on the remote, you are not going past the blue Press OK screen?  Is the ATT button (top left) pressed (and blinks red) when OK is pressed?

What happens if you press the OK button ON the front of the DVR?

Another thing you can try is to unplug the DVR at the back of the unit; wait for the 3 front lights to flash (a few seconds) and plug it back in.  That should not cause you to loose your recordings and is another way of doing a soft reboot.

Kitty sounds smarter than the tech you got, sad to say.

The USB ports are not turned on at this time for an external HDD, but might be in the future.

Others here can give you some tips on making HDMI work.