Faulty Laptop Tx2500

hiii..
i have one laptop pavillion tx2500...
but got problem with the lcd...
when i open the power button, bios hp was display is a few second n then black screen is back...i think is faulty screen,,,,but when i use alternative to joint with external monitor dekstop, windows can display perfectly and can use without nothing problem...

Sometimes that lcd can display for long time...but when shutdown...n turn again, it coming back the problem...

i donno why..cause the board is excelent condition.

anyone can help me....PLeaseeeee....