Amazing that a company, whose primary purpose is an operating system, and has been around for decades, can't even turn the computer off correctly. This company is literally evolution in reverse.

If I had to take a guess it's that one of the device drivers for a random component on the board is keeping it on which prevents the main power from turning off. There has been a similar bug for many years where some users report having to shut down or enter hibernate two or three times for it to stick.