No video on E6420 screen prior to Windows 7 loading.
I just installed Windows 7 Pro and all drivers on an E6420. After updating to BIOS version A16, NO video image appears on the laptop screen prior to Windows loading. On either cold or warm boot, neither the Dell logo, the BIOS version, the progress bar, nor the F2 or F12 prompts are seen. I can get into the BIOS if I'm lucky enough to be pressing the F2 key at the right time, but none of the BIOS information appears on the laptop screen, either. I know this because when I connect an external monitor to the external VGA connector on the side of the laptop (not using a dock), I see the Dell logo, F12 prompt, etc, on the external monitor for about 1.5 seconds and I can press F2. I can also see all the BIOS setup information on the external monitor. If I disconnect the external monitor while in the BIOS, the image does not then display on the laptop screen, it remains blank. I've found no current posts on this problem. If anyone has an idea how to get the video to work, I'd appreciate any and all help.
Also, is it normal for the POST screen to display for such a short time? The BIOS Fastboot setting for POST Behavior is set to thorough, but the display time for the Dell logo, F12 prompt, etc, is still very short. Thanks in advance.