FAT-fs (/dev/sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

# Install utility for making and checking MS-DOS FAT filesystems.
sudo apt-get install dosfstools

# Execute the following
sudo fsck.vfat -v -a -w /dev/sda1

dosfsck 3.0.13 (30 Jun 2012)
dosfsck 3.0.13, 30 Jun 2012, FAT32, LFN
Checking we can access the last sector of the filesystem
0x41: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
 Automaticaly removing dirty bit.
There are differences between boot sector and its backup.
Differences: (offset:original/backup)
  71:53/2d, 72:50/33, 73:49/32, 74:4b/47, 75:45/42, 76:53/20, 77:2d/20
  , 78:33/20, 79:32/20, 80:47/20, 81:42/20
  Not automatically fixing this.
Boot sector contents:
System ID "BSD  4.4"
Media byte 0xf8 (hard disk)
       512 bytes per logical sector
     16384 bytes per cluster
        32 reserved sectors
First FAT starts at byte 16384 (sector 32)
         2 FATs, 32 bit entries
   7590400 bytes per FAT (= 14825 sectors)
Root directory start at cluster 2 (arbitrary size)
Data area starts at byte 15197184 (sector 29682)
   1897568 data clusters (31089754112 bytes)
32 sectors/track, 255 heads
         2 hidden sectors
  60751870 sectors total
/SHARES/02-20170802072122.avi
  File size is 1293488 bytes, cluster chain length is 655360 bytes.
  Truncating file to 655360 bytes.
Reclaiming unconnected clusters.
Checking free cluster summary.
Free cluster summary wrong (1888494 vs. really 1888533)
  Auto-correcting.
Performing changes.
/dev/sda1: 137 files, 9035/1897568 clusters