Lcd screen- bright is low

There could be a couple of reason why laptop didn't start-up. Basic: the battery is dead and need to be recharged. Possibly the battery isn't keeping charge and the AC power charge is un-plug from the wall. Leaving the laptop without power. Make sure everything is plugged in and try to power it up. It that doesn't work then it could be the power supply in the laptop it self. Good Luck!!!

Try attaching an external monitor to the laptop & see if you could get any display on it. If this is successful, then you might have either a faulty LCD cable or screen inverter board.
The LCD cable transfers data signal from the motherboard & video card to the LCD screen. It also supplies high voltage DC power to the screen inverter board. The screen inverter board works as a power supply for the backlight lamp mounted inside the LCD screen. It converts low voltage DC power to high voltage AC power needed for the backlight lamp.

it would be on the motherboard
under they keyboard, looks like a watch battery,
with a little plug maybe coming out of it , pull plug to disconnect

Defective CCFL backlight, it may have the following symptom: Screen flashs on red/pink and off. Picture stays on in red and slowly be come normal. Picture flickering with dim display or appear black. Picture flickering on and off. All these symptoms indicate that the LCD backlight lamp (CCFL Lamp) has reached the end of the life and all you need to do is replacing the CCFL lamp.
Connect an external monitor to your laptop and power the monitor up first then the laptop, if you see the normal Windows images then the video card and laptop is OK and the problem is definitely the backlight. Dim image and/or dark display on the laptop's LCD screen indicates a faulty LCD backlight and it could be the inverter that supplies high voltage to the CCFL lamp or it is the CCLF lamp is nearly burnt out or burnt out, most likely this is the case.
The inverter can be replaced easily but the CCLF lamp is more time consuming and requires soldering skills.
Check out
www.lcdparts.net
for parts, repair service and DIY info.

A few things to try. First turn on the unit, and after it seems to have booted up (like at a windows login or something), take a flashlight and in a darkened room shine it on the screen. If you can see a picture, it means your backlight is out. Go on ebay or elsewhere online and look for an acer aspire 1690LCi backlight. Then open up your screen and replace it (there should be tutorials online for this). If you don't see an image, your screen maybe be out or have more serious problems (video card, LCD dead, etc.).

Sounds like your number lock maybe be on. It could also have a shortcut function option that is on. If not, have you spilled anything on it lately?

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Your screen sounds fine, most likely just your backlight going out, either that or you could have hit the key for using an external monitor (function f6 is the LCD/external monitor switch for my computer). I'd look into the function f6 and play around with that, if not you can just buy a new backlight from ebay or an internet supplier.

u have to chek power menajment in in advance power menagment. show in just rign click on dektop then propeties>screen sever>power or advacne> chek power schem is alwase on.. it's help u...

back up your personal info, pictures, docs, all that you need conserve. Format the computer and install english operating system.
Good Luck