Laptop Backlight Not Working

[azuredave04]

Hello!

I recently picked up a Compaq Presario CQ40-108TU online. The seller mentioned that the screen backlight is not working while the rest of the laptop still work fine. I tried replacing different displays as well as inverters but nothing seems to work, I didn't check the display cable because I don't think that's the problem. I also disassembled and cleaned the laptop up with a brush and some isopropyl alcohol but it didn't help either. One thing I notice when installing Windows through an external monitor is that, the system is very unstable. I created a Vista bootable USB drive and plugged into the laptop, it randomly freezed the loading bar for a few seconds. After passing the language & format window and into the disk selection, it displayed “A required CD/DVD drive device driver is missing. If you have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now.” error (which I have never seen in any previous CQ40 I acquired). I suppose the problem is coming from the motherboard, or the BIOS (the BIOS version is F. 11C to be precise). So I wonder if somebody can help me fix this backlight problem. If it is exactly the old BIOS version, how can I upgrade the BIOS via USB drive. Thank you!

[banhien]

@azuredave04 

I can not find its official specs but a decade old machine does not have backlit keyboard (I owned an Elitebook, it has a light next to its camera for keyboard)

                 

Does your machine have any key with backlit symbol     ?   If not, you can use something similar to

                         Computer Keyboard Laptop Flexible USB LED Light

That is a very old machine from previuos1 or more users, only God knows what was going on. I don't have machine with me therefore I can't comment more.

Regards.

[azuredave04]

Hello sir!

First of all, I think that you might have a complete misunderstanding of what I'm asking about. What I meant is the backlight of the display somehow is not working. My laptop has a LCD display, along with an inverter under it to power the display. Unfortunately, the laptop boots up just fine but the screen is very dark and I can't see anything. I have tried many working displays and inverters (those are from laptops I know functioning) but it doesn't fix the problem. I think maybe old BIOS version might be the cause (the version is F. 11C while the latest is F. 66A)

[banhien]

@azuredave04 

Sorry, I was thinking about the KEYBOARD backlit. Now, you need to se a repairer and ask him/her to physically check and replace the screen if required.

Regards.