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This board sometimes chime but no video and when I have video it ask me to replace the password. I replaced the HDD and now works always. Thats make sense? Never seen that in WIndows laptops.
When power on without video, no backlight, no video. Only chime.
Probably EFI locked. This can fool with backlight on some units, too, because you can't PRAM reset. Board will (most likely) need to be unlocked before you can proceed to reset PRAM. Backlight more than likely works fine, but hard to know with lock on board.