John Rumm explained :
Might be worth checking if there is a BIOS update for it - some older
machines can have odd screen related issues like this with Win 10. I had
similar on an old (but high end when new) Dell Inspiron recently. Converted
it to 10 from 7, and it worked fine up until it found a new display driver to
match the hardware. After that, it just gave a blank screen on the internal
LCD after booting (but was still fully functional on an external monitor or
via remote control). A BIOS update sorted that.

Thanks, I will take a look at that..