If with Brightness turned all the way down, you still see the dim screen. Not a black screen.
Basics from the manual are restart, reset, restore
Follow the 3R's- if a restart does not solve your problem proceed
User troubleshooting is:
1.restart, ie power off/on,
2. reset http://support.apple.com/kb/HT1430,
3. restore from backup, restore as new device. http://support.apple.com/kb/HT1414