A friend lent me a little used RPi 4B to try it before to buy it. I am not sure to buy it but for now I simply connected a display and powered it.
By bad luck I noticed that my only monitor that handles HDMI no longer works, so I can not see what the device is displaying.
I found with nmap that the RPi could be accessed by SSH. I attempted to login to it with the default credentials for user pi but these does not work. So I asked to my friend the working credentials which do not work anymore.
So I plugged in a USB keyboard, its LEDs indicated that it was operational and I tried the Magic SysRq Key REISUO combination but I must have made a mistake or the combination is not exactly the same on a AZERTY keyboard (I'm French) because now not only the device has not turned off but the keyboard LEDs are no longer lit. Even when changing ports nothing happens.
I saw an ultimate proposition which indicates to unplug the power (as my ACT LED is not lit and is not blinking) which can work ... or not !
As the device not belong to me, I wish to know if someone have a newer or a better solution to shut down safely without risking corrupting the system ?