My device became inaccessible recently. I did not do anything unusual, so I am guessing that an automatic software update failed. The LED was a rapid blinking blue. A “power off 40 second reset” did not change the behaviour.
There are a few forum posts that discuss these symptoms and offer various solutions. Some links to required software are obsolete. I downloaded these:
Putty
usbrecovery.tar.gz
One of the threads contained a link to this video. I followed these instructions up to 3:35. Putty showed a list of errors and asked for permission to fix them; I replied Y to each message. I rebooted.
This fixed the problem. The device is behaving normally.
This is Putty’s log:
…
/ # e2fsck /dev/sda3
e2fsck 1.42.13 (17-May-2015)
/dev/sda3: recovering journal
Superblock last mount time is in the future.
(by less than a day, probably due to the hardware clock being incorrectly set)
/dev/sda3 contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 16 has zero dtime. Fix? yes
Deleted inode 17 has zero dtime. Fix? yes
Deleted inode 18 has zero dtime. Fix? yes
Deleted inode 19 has zero dtime. Fix? yes
Deleted inode 20 has zero dtime. Fix? yes
Deleted inode 21 has zero dtime. Fix? yes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -(32832–34217) -(34816–58907) -(61440–65535) -(69632–89681) -(90112–98303) -(100352–155737) -(157696–163839) -(165888–199770) -(200704–207963) -(208896–229375) -(231424–249855)
Fix? yes
Free blocks count wrong for group #1 (1424, counted=30998).
Fix? yes
Free blocks count wrong for group #2 (0, counted=28242).
Fix? yes
Free blocks count wrong for group #3 (532, counted=31252).
Fix? yes
Free blocks count wrong for group #4 (0, counted=30810).
Fix? yes
Free blocks count wrong for group #5 (532, counted=31252).
Fix? yes
Free blocks count wrong for group #6 (0, counted=30903).
Fix? yes
Free blocks count wrong for group #7 (930, counted=19362).
Fix? yes
Free blocks count wrong (4096, counted=203497).
Fix? yes
Inode bitmap differences: -(16–21)
Fix? yes
Free inodes count wrong for group #0 (8042, counted=8048).
Fix? yes
Free inodes count wrong (64490, counted=64496).
Fix? yes
/dev/sda3: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sda3: 16/64512 files (6.3% non-contiguous), 54551/258048 blocks
/ # reboot -f
