My nintendo ds lite powers up green light comes on but screens stay black

problem with the main board inside of the DS Lite. Its not staying on with the voltage being provided. To verify this. Plug your DS Lite into a working outlet and see if it stays on.

If it doesn't stay on then take the battery out and only hook up the ac adapter to it and see if it stays on.

At that point if it doesn't stay on, try to use another AC Adapter to see if it stays on, if it doesn't then you know for sure the main board is bad and you would need to get a new ds lite.

Sounds like the processor has gone on the mainboard.
Using r4 or similar card? if so these burn out the board sometimes.

well go online type get ds fixed the they will tke it for 2 days

Maybe the cables from the chipset to the screens have come loose??

One or both your screens have blown.

Try removing the motherboard from the screens and attach the battery the green light should turn on and stay on.

Now attach the lower screen and turn on. If the screen is ok the screen and green light will flash and then turn off. (if the screen doesn't flash the bottom screen is you're problem and will have to be replaced)

If this happens the problem is then you're top screen which you will have to replace.

The alarm is just a coincidence i suspect, green light comes on and stays on probably not the battery at fault. It would be red.
If the green light goes out and screens just flash one of your screens are at fault or a loose ribbon connection.

For GBA games the green light is meant to stay on. The orange light will stay on as long as its recharging. It will turn off when its fully recharged or when you unplug it

When you boot the Nintendo DS you can change the illumination settings in the main menu.
One the main menu, you will find a sunny symbol in the lower left corner of the screen. Click on that and you should be able to change the level of illumination. If you are also wondering if you can change the brightness during game play, you can't. Games such as Mario 64 DS come with support for brightness change but otherwise you have to do it before game play.

Ditto... except my daughter is 10. Both screens remain black, are fully charged and green light stays on for more than 4 minutes.

did you drop it a lot? If you did you may not be able to fix it...