My laptop (a latitude 6520), displays a black screen and shuts down without warning or explanation. It does so within 20 minutes of booting up. Sometimes it's more, sometimes it's less.
I connected my laptop to a monitor and set the display on the monitor only. Within a few minutes, the monitor went to a yellow screen and my laptop again shut down.
Windows Event Viewer doesn't provide any insight, other than an improper reboot.
I ran the BIOS test and and the LCD cable test failed with error code 2000-0415. The display works fine before the laptop shuts down. Is this failure causing the shutdowns?