Not sure, but are you saying that the problem is only intermittent and that the display does finally appear?
Try the following checks to narrow down the possible problem
Turn on the laptop and allow it to boot. Then shine a torch at an angle close to the laptop screen and check if you can detect a display . It will be very faint. It might help if you tried this in a darkened room.
If you can detect a display then there is a screen backlight problem with the laptop. This could be caused by a faulty backlight power supply , a faulty lid switch, a faulty video cable (try either moving the lid back and forth slightly or gently pressing the hinge area between the lid and the case to see if anything happens, this is where the video cable passes through to the display), faulty video cable connections at either end (motherboard or screen) or a faulty LCD screen.
If you cannot detect a display connect an external monitor to the laptop and see if there is a display showing on it.
If there is a display on the external monitor try booting in safe mode and see if the laptop screen works OK immediately. If the screen still doesn't work immediately in safe mode then the problem could be a faulty video cable, faulty video cable connections at either end (motherboard or screen), or a faulty LCD screen.
If there is no display on the external monitor then the problem is either a faulty GPU or motherboard.