I have a new z500 that I've downgraded to Windows 7 64bit. For the most part I have everything working. I accidentally hit the brightness + (yes, +) and it instantly dimmed the screen to where it is barely viewable. It seems that hitting that one key decreased the brightness to the minimum amount. I've rebooted, looked for a setting in the BIOS, hit the Brightness +/- and can't increase the brightness.
The other hot keys work correctly. I've tried increasing the brightness via the Control Panel, but nothing seems to work. The screen is extremely dim whenever the machine is powered on (including the BIOS), not just in Windows. I tried a lot of intel chipset drivers, the available Intel HD 4000 drivers in Win8 and win7 too, but nothing working.
Is there a way to get this fixed and working normally again?
The issue is associated to a windows update over the driver itself. It is highly recommended to check the updates from the windows updater before you installing.
Go to device manager
Select Display adapters and scroll down
Right click on Inter(R) HD Graphics4000 and select propierties option
Go to tab Drivers in the pop up window
Push the Rollback Driver button
Wait until it is done Your system should recover the brightness and the increase/decrease functions in the keyborard.