Nikon d40 display not turning on

try another new battery, maybe your battery is dead.

DC-DC or Main PCB failure or both wrong.Send to Nikon Service.

That's the way the D40 works. The monitor is for menus and picture review, not to show images before shooting. Nikon introduced the LiveView capablitily with the D3 and the D300, introduced after the D40. The D40 works as SLRs have worked for half a century, giving you the image through the viewfinder.

Do you have review turned off?

Try removing the battery and reinstalling it. Also try reformatting the memory card.

You have a short in your button board in your camera or a bad button board. Send into Nikon to repair. You can also look on Ebay for the part if your technical skills are up to self repair.

with the histogram visible on the screen, simply press the "down" arrow on the navigation dial. This will scroll through several on-screen options, until you get back to the playback screen you want

If you were seeing the image before you shoot, there was definitely something wrong with your camera.

The D40 does not have a Live View feature. The display is for menus, shooting information, and image review. Not preview.

According to Nikon, that was not possible. The D40 doesn't have 'Liveview' like the smaller compact cameras. You would always have to use the viewfinder for taking pictures. Even in the TV ads, everyone used the viewfinder as they took turns using the camera.

Here is a link to Nikon's web site: NikonUSA

Try pressing the "info" button on the top of the camera next to the shutter button. This turns the LCD off and on to save battery life.