Dell Inspiron 5110N (Display on boot up turns grey)

I have tried removing the battery and power cable, holding the power button on for 20 seconds then connected the power cable and re-inserting the battery.
The problem still remains.
I can attach an external monitor and press Function and F1 on boot up.
The monitor works and the machine will boot up.
I get no beeps or other indications upon start up other than the Dell logo flashes 
for an instant
I have replaced the LCD screen and tried a restore.
I understand that there could be a bios issue with this model Dell laptop
that could cause this issue.
Am I missing something?
Thanks