My camera has a black screen even when is on

When the battery is fully charged, please put it in again. That means, if it is still in, remove it once again.
Switch it on, and even if you don't see a thing try to make a picture.
Then press the display button several times, to see if anything comes on the screen again.
If the camera does not respond after that, you should go back to the dealer, of contact Nikon.

its just a matter of batteries...some are not powerful enough to operate the camera ....Try to change them and buy some real good ones..like Duracell or Tatra...do not make any compromises when buy the batteries...get the best cause these kinda cameras really require powerful ones...or ...try to get a set of rechargeable ...

Are you using the batteries recommended by the manufacturer? that is a very important fact, even though you can find other batteries that have the same specs, they make the cameras to where it will work best, and sometimes only, with the batteries recommended.

It may be something more serious, or your new batteries may be defective, but the problem you describe is frequently due to corrosion on the battery contacts inside the camera. Remove the batteries and wipe the camera contacts firmly with a clean cloth (heavy corrosion buildups may require cleaning with a wire brush, steel wool, or sandpaper). Remove any residue that may have fallen into the battery compartment, clean the contacts at both ends of the batteries, and reinstall them in the camera. Assuming that the batteries are fresh/fully charged, this takes care of about 90% of the startup problems. I hope it works for you.

It could be that you have the auto power off set to a short time like a minute

try looking at the symbols on the battery and then on the camera and try putting them in that way and if that doesnt work try an other brand of batteries

Was the camera turned off, it must be turned on and set to USB to PC in settings menu.

It's not the battery. It turned out to be a memory card problem.

I took out my old memory card and put in a new one. It started working properly after that.

simple! with my Canon S90 had the same problem until I changed the SD card from LEXAR for a TOSHIBA SD card and the message " Change the Battery Pack"disappeared.

SOLUTION: Fot the past two years, fully charged NiMH and new alkaline (generic and fresh Name Brand batteries) in my CX7530 always gave a red light and immediate power off -- symptoms of low batteries. Today I tried it again with the same problem. This time, I folded up a small piece of stiff paper to depress the small Lithium battery module detect switch in the battery compartment, and put my NiMH batteries back in -- it WORKED for the first time in two years! After removing the paper and reinserting the batteries, it still works. I suspect this somehow recalibrates the low battery detect circuit. I hope it helps you as well.