Unable to mount /var/lib/sudo/olimex/O Read-only file system

[universe]

Hello,
I've just downloaded the official olimex debian R9 image. And I failed to change the screen resolution, with error Unable to mount /var/lib/sudo/olimex/O Read-only file system after entering any sudo command. How could I fix this please?
Thanks in advance

[universe]

I tried the R8 image and it boots only once and the second time it stalls (apparently the boot is getting damaged after proper shutdown, as I flashed it twice and the same synario occurs).
My SD card is Samsung 16GB Class6, my hardware is the A13 WIFI version.
Thanks for your support.

[universe]

By the way the default VGA screen resolution is 800x600 not the 1024x768 mentioned in the wiki page https://www.olimex.com/wiki/A13-OLinuXino#Linux, there is also some typos about the image name. I even removed the archive attributes from script.bin and uImage. All the system is Read-only I cant change anything!

[MBR]

You don't need sudo, just use su, become root and remount the filesystem read/write. But there is probably a reason why the filesystem is mounted read-only, so you should check it first by fsck.

[universe]

Hello,
First of all thanks for your reply, sorry for being late as yesterday I didn't have access to internet. The issue was a bad SD card. Thank you.