Display black on first boot

[James3]

Press the chassis open switch in the center of the Mainboard 10 times. 2 seconds on, 2 seconds off, repeat 10 times. This is done while the laptop is switched off, but with the power cable newly connected.

There is a picture of the “chassis open switch” in this thread:

[SOLVED] Spurious keystrokes (and I don't think it's the keyboard)

Press the chassis open switch in the center of the Mainboard 10 times, you must press it slowly, so press for 2 seconds. Release, wait for the red blink on the Mainboard LEDs. repeat. Stared at my mainboard for 2 solid minutes. What’s the chassis open switch look like? (Or where can I find a guide that tells me)