Screen is dim upon reopening notebook

If your screen is dim or off when you open your notebook while it is still powered on, first check that the system hasn't gone into standby mode or hibernate to save power. Pressing the space bar will return the system from hibernate and function key plus the F key that shows a moon type icon will return it from standby.

Should the above not turn the screen back on or if you can see a very feint picture, it could be that the small switch that detects whether the screen is up or down may be sticking. Often this is because of dust or dirt in the mechanism. It is usually possible to free it up by pressing it down or lightly brushing it to remove any dust.