WHEN I BOOT UP MY APPLEIBOOKG3NOTEBOOK THE SCREEN STAYS BLACK BUT I CAN HEAR SOUND AND ALL THELIGHTS COME ON

Sounds like your video chip or your backlight. Hook up an external monitor. Does it stay on or the same results.? How long before it goes off/BLACK ???

Have you zapped the p-ram? Hold Apple, Option, P and R keys when you hear the chime. Wait for four more chimes and release.
Try "detect displays" from display preferences. In system preferences, displays, be sure brightness control is turned up.

If it has no sounds of say music that you would hear of its system launching then its possible its Back up battery has failed an scrambled the Bios, this is a disc like lithium battery in a holder
How to Install CMOS Battery in Gateway Laptop Gateway Netbook disassembly LT2802U

These may help you though I have not seen where its located but that second link might give a clue if you watch it through.

Hope this helps..........

Monitor is connected (power and signal), turned on?

hello..this is the 1st you need to try..if you have a CRT monitor or LCD Screen try to put the signal Video on the Laptop located at the Back of unit then try to boot your unit...Thanks...

does it make the boot up sound? if so its a fault with your screen..can replace screens for £7.50 off ebay. try re- inserting ribbon cable for screen b4 buying new screen tho (could be that). if you can't hear bootup sound when powering up then something else wrong. maybe F1 or F2 fuse blown (test with a multi meter) look on youtube for tutorial

It sounds like your PC isn't completing its POST. (pre operating system test)

This is usually caused by faulty hardware. Your best bet is to first remove anything you have recently installed. If that doesn't apply/work, try removing various hardware devices (CD/DVD drives, memory, USB devices) until you get the machine to boot up.

If even after removing every piece of hardware possible the machine still exhibits the same behavior, it is likely a problem with the motherboard (or other "permanent" hardware).

Try disambling the system. Clean it with a wind blower. Check BIOS battery capacity. Replace if possible. Power on the laptop. Do you hear humming sound from hard disk ? If you hear sssssssshhhhh sound from hard disk; it's OK. Replace RAM with new one. If problem still exists Than change main board. Hope that not happen. Keep informing.

Repaired! This sounde like a fuelty screen or screen inverter. To check this, connect to an external monitor, if the external works properly, then it's the screen or inverter. If the external doesn't work, let me know and we'll run the problem down to a more indepth (internal) trouble shoot.

You said that you hear a series of beeps, if you hear this kind of sounds maybe there is a loose connection from the CPU. Try to remove the Memory and put it back again.

Mon =)