Black screen after installing more RAM

After installing more RAM the laptop turned on to a black screen. There was no response to Fn keys, no Fn Lock LED, no mute LED, couldn’t get the keyboard to light up beyond the initial flareup/flaredown. After 45 seconds and the system restarted normally. It seems there’s some kind of self-check the laptop runs once upon RAM size change. Too bad they don’t put a “RAM testing” notice on the screen to avoid panic of the user!