Micro SD cards used by the raspberry pis are cheap but prone to failing

If the system won't boot and the SD card is read only it may have failed. Best way is to buy a new micro SD card (16 or 32GB) and restore a backup

I have uploaded an image of nnrpi2 (AIDA@GSI) to aida-3 (/home/npg/nnrpi2.img)

To backup an SD card

dd if=/dev/mmcblk0 of=nnrpi2.img status=progress

To restore a backup to a new SD card

dd if=nnrpi2.img of=/dev/mmcblk0 status=progress

(/dev/mmcblk0 name may differ on different machines, is for a laptop with built in SD card reader)