Laptop acting strange at shutdown or at boot, caps lock light on for a few seconds

[Michaël]

Hello everyone.

Recently my laptop is acting weird.

Sometimes when I ask for a reboot, it doesn't reboot. It just shuts down and when this happens, the shutdown sequence is weird as well.  The lights for Wifi and Mute go out first, and then the power light and after that the Caps Lock button lights up for some seconds. The same thing happens when I shut down (no reboot expected of course, but the next boot is much slower). Also, when it happens the computer won't power on when the lid opens. 

I already tried a clean install, the problem persists. 😕 

If someone could tell me in which direction I have to look for a solution, it would be a huge help!

So if someone could say what the caps lock button at the end of the shutdown sequence means, thanks beforehand!

[Michaël]

Update: what I also tried is the HP 4 in 1 usb stick with the HP UEFI hardware troubleshooter on it. It couldn't find any issues. I have absolutely no idea what caused it, because when I put a new ssd in it I did it on a anti-ESD mat while being earthed correctly, like I always do it.