I've been experiencing strange boot errors from a USB device, and can't get the error message because the boot screen scrolls off the screen too quickly.  Are the boot messages logged somewhere?

 

Is there a way to test my Unraid USB boot drive?

 

I tried dosfsck and noticed some strange messages:

# dosfsck -av /dev/sdb1
fsck.fat 4.2 (2021-01-31)
Checking we can access the last sector of the filesystem
There are differences between boot sector and its backup.
This is mostly harmless. Differences: (offset:original/backup)
  65:01/00
  Not automatically fixing this.
Boot sector contents:
System ID "SYSLINUX"
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
   7830016 bytes per FAT (= 15293 sectors)
Root directory start at cluster 2 (arbitrary size)
Data area starts at byte 15676416 (sector 30618)
   1956999 data clusters (32063471616 bytes)
63 sectors/track, 255 heads
         0 hidden sectors
  62654593 sectors total
Reclaiming unconnected clusters.
Dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
 Automatically removing dirty bit.
Checking free cluster summary.

*** Filesystem was changed ***
Writing changes.
/dev/sdb1: 4618 files, 67350/1956999 clusters

# dosfsck -av /dev/sdb1
fsck.fat 4.2 (2021-01-31)
Checking we can access the last sector of the filesystem
Boot sector contents:
System ID "SYSLINUX"
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
   7830016 bytes per FAT (= 15293 sectors)
Root directory start at cluster 2 (arbitrary size)
Data area starts at byte 15676416 (sector 30618)
   1956999 data clusters (32063471616 bytes)
63 sectors/track, 255 heads
         0 hidden sectors
  62654593 sectors total
Reclaiming unconnected clusters.
Checking free cluster summary.
/dev/sdb1: 4618 files, 67350/1956999 clusters

 

Thank you.

tower-diagnostics-20230920-2304.zip

Try backing up and reformatting the flash drive, if the same try a different one, also make sure it's using a USB 2.0 port.