Hi, my RPi system works well all the while, until I’m using Putty (first time) and prompted by a message warning you that you’re attempting to establish a connection with an unknown host. I have pressed YES to proceed. After entering the system, working on some commands and then typing “sudo shutdown -h now” to exit, I’m not able to enter the RPi again.
Kindly advise what should I do to enable my system again? Thank you.
That command will shut down your Pi.
So, you won’t be able to establish a connection anymore until you power the Raspberry Pi again.
You need to unplug the power and power it again to boot.
Yes after shutting down, I’m not able to power up again, the ACT led is no longer blinking. I’m using Raspberry Pi 3 B+.
Will putty modify my system file on my RPi when I pressed “YES” on the message warning that ” attempting to establish a connection with an unknown host” on Putty?
That’s weird. It seems to me that you have a problem with the SD card.
I found this:
Check the ACT LED
There’s a green LED on the corner near the power supply input that blinks when the SD card is being accessed. It’s labelled ACT, and it can be used to determine whether or not the SD card can be read. The LED should blink erratically when reading from the card during the boot process. If it’s not blinking when the Pi is switched on, it means the card cannot be read.
You may need to install the operating system again or use another microSD card. If you get the same issue you may have other boot problems. Check this link that shows common boot problems.
I hope this helps.