SM W720: Display remains dark starting the system

Hello Samsung, 

more and more I have difficulty to restart my w720 after having shut it down properly via Windows shut-down. 

The display remains dark, 

but the LED on top blinks dark and bright blue. 

The keyboard background lighting is on. 

I can shut the system down again (keyboard background lighting off) by holding the on/off key about 10 seconds. 

Sometimes it comes up by booting, but I cannot recognise a systematic behaviour. 

Folks, I don't want to waste minutes and minutes until the system comes up in my eyes accidentally. 

I found another thread (https://us.community.samsung.com/t5/Tablets/Original-Galaxy-Book-won-t-Boot/td-p/1577031), however, it does not answer my questions, how to start the system consistently, what does the bright/dark blue blinking mean; also I did try the 'Reset the video driver. Press Ctrl + Win + Shift + B. The screen may flicker as the video driver is reset.', but obviously only works when the system is up and running, but does not influence the behaviour after shut-down and my restart trials. 

Thanks in advance, 

AB