It says the SD card is write protected even if it is in unlocked position. I'm trying to recover lost password by following the instructions here http://www.raspberrypi-spy.co.uk/2014/08/how-to-reset-a-forgotten-raspberry-pi-password/
You did not remount the root file-system
/ (with the command
mount -rw -o remount /) so you cannot change the
/etc/shadow files concerned...! Also, in that article, I'd recommend reading the comments as well.
The solution was rather funny, to say the least. The lock switch on SD adapter was not supposed to go all the way into unlock position, but be placed somewhere between 0.5mm and 2mm away from the unlock position towards the middle. Really unbelievable. I hope this saves someone some head scratching.