This is on an outdoor power receptacle that looks like it should be some kind of timer for switching power on/off. I'd love to use this for Christmas lights, but I can't seem to get it's little display to light up regardless of what I press. Does anyone know what this is so I can find a manual online?
This is a GE device, though I think a Leutron or Leviton also make a pretty similar unit. Here's a link to it on Home Depot's website.
My experience with these units is that they fail very rapidly - I went through 3 of them in a year before I switched brands. You can see the comments on Home Depot echo this. They also can fail closed so that with a dead switch, everything is still powered and you have no way of turning it off - quite annoying if you ask me!
I would recommend that you replace it with another brand. They are not serviceable.
I agree that it is definitely a timer for controlling the adjacent outlet. Have you tried activating the reset button by pressing it with a sharp tool (even a pencil)? Then try pushing and holding the clock button. If that works, you should be able to set the hours and minutes using those buttons. Then pushing the program button should allow you to set the timer on and off times. If this doesn't work, try cycling the bottom slide switch from off to timer. If nothing works, it may be that no power is getting to the timer and/or the outlet. Can you check that the outlet has power on either position of the slide switch. If not, then you need to check further as to how the outlet is getting power (perhaps a fuse or breaker is off). One way to check is to push the check button the GFI that is part of your power socket. That should cause the reset button on the outlet to pop out. If that doesn't happen, then either the socket does not have power or the GFI is defective.