I have the same issue with mine, can't turn the screen on and off again unless i unplug it.
Is there a 3rd party PSU that will do the job? I did see somewhere that the PSU used for their laptops is the same as this? dunno if thats true?
I bought 19V 4.74A 2.5MM ASUS G1SN GENUINE AC ADAPTER CHARGER for £13 and it solved all issues