Screen stays bright for a time and then fades to light

it must have been in auto brightness mode. once check it.

chek buttons if possible can remove buttons cable

Its probably not the screen at all. It could be a bad LCD converter module. Or even a failing graphics card. I would suggest taking it in for a checkup at Best Buy or a local repair shop for further trouble shooting.

The brightness of the screen on battery and on AC power is configured in the pre-OS setup.
When the computer starts you will see options like press F2 or DEL to enter Setup.
Choose this option and you should find your brightness settings.
Two points:
Lower brightness saves battery power.
Your notebook display will fade over time. You might be able to find a replacement at eBay. If not, I am sure Dell will fix it for you.
I hope this helps.

The unit automatically adjust to ambient room brightness within user-selectable limits. The minimum might be too low.

Page 20 shows how to adjust the minimum brightness.

http://worldwide.bose.com/productsupport/en_us/assets/pdf/guides/wave/wr_series2/en/owg_en_wr_series2.pdf

Does the light associated with the hard drive flicker, stay on and then fade sometimes? If so - then the hard drive is working and the likely problem is a faulty screen. You can also try the function key plus whatever F key would increase screen brightness. (i.e. Fn + F7 on my machine.)

Have you checked the brightness options for the screen using the HP function keys? Fn +F7 or Fn+F8 should adjust the brightness of the screen for that C306 model laptop. If adjusting the brightness has no response then try the next steps.

What happens if you turn the computer off, plug it into an external monitor or projector, and then turn the computer back on? If the video displays correctly on a computer monitor or projector, but it stays dim on the LCD screen of the laptop, then the laptop LCD Screen Back-light or inverter is probably going out. You'll need to contact HP for a replacement part or take the laptop to a certified repair center.

hi verifies if you are connecting good the video cable i mean the red, the yellow, and the white, if this dont serve you, is because your tv is to old.

time for a new lamp i'm afraid.

I don't know for sure if this will help but it's worth a try. Go to Start, control pannel, system, advanced, performance, settings, and click adjust for best performance. This is a Windows XP fix but the same thing may apply to older OS's (95, 98, 2000, ME, NT (although you may have to set it a diferent way). Many other things could be your problem but this is an easy thing to try.