Notebook does not shut down properly after cleaning the fan?

After a while I dusted my notebook, also with success, the performance is back to the end level, but one thing is strange now…

if I shut it down normally, the screen goes off after a few seconds, the mouse too, but the keyboard continues to light up and the external and internal fans also stay on… I have to press the power button to turn it off properly hold…

What I still have to mention, the cleaning itself went smoothly, but when I turned the device a little, a small screw, approx. 5mm, came towards me, but could not identify where it came from… Then I put the cover back on made and the screws in… As I said, everything is perfect… Only that is now weird

I mean maybe you can see if you can find a loose cable or a bad connection or something else but otherwise just stay on it for a long time unless the laptop is brand new now

It's quite old, but it's still stupid if it suddenly happens… I also find it strange that just one screw was apparently loose… But there wasn't really anything loose…