[PROBLEM] Moode won't start if a USB stick with music is present

[TheOldPresbyope]

I second Al's suspicion that the USB stick with music is marked as bootable. (As always, one has to keep in mind that if the power supply is inadequate, then all sorts of weird behaviors may occur but it sounds like this isn't the case here. One can always check the logs for undervoltage events.)

I routinely run test scenarios, including on a Pi3B+, which boot moOde from one USB stick (actually a uSD card on an USB adapter) and contain test tracks on one or more additional USB sticks. This approach has been working for me since the RPF introduced the ability to boot from USB.

Regards,
Kent

Thanks to both of you. I use 64 Gb Sandisk  Cruzer sticks, NTFS format.
I wasn't aware that a USB stick can be marked as unbootable, despite quite a few creations of loading music on an empty stick.  How do I achieve that?

Well, it's still just a conjecture on our part that I'll try to test later today.
 
Meanwhile, from the command line you can run fdisk as superuser and look for an asterisk under "Boot" in the device entries. For example, here's the output for one of my players when I ran fdisk with two USB sticks inserted. One with two partitions and one with only one partition, so there's a total of 3 entries listed in the "Device" groups, none marked bootable. The -l flag means "list" and the /dev/sd* means look only at these removable drives (loosely speaking).

Code:

pi@moode:~ $ sudo fdisk -l /dev/sd*
Disk /dev/sda: 14.84 GiB, 15931539456 bytes, 31116288 sectors
Disk model: STORAGE DEVICE  
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xb9f96b7c

Device     Boot  Start      End  Sectors  Size Id Type
/dev/sda1         8192   532479   524288  256M  c W95 FAT32 (LBA)
/dev/sda2       532480 31116287 30583808 14.6G 83 Linux


Disk /dev/sda1: 256 MiB, 268435456 bytes, 524288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000


Disk /dev/sda2: 14.58 GiB, 15658909696 bytes, 30583808 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/sdb: 28.64 GiB, 30752636928 bytes, 60063744 sectors
Disk model:  SanDisk 3.2Gen1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot Start      End  Sectors  Size Id Type
/dev/sdb1          32 60063743 60063712 28.6G  c W95 FAT32 (LBA)


Disk /dev/sdb1: 28.64 GiB, 30752620544 bytes, 60063712 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000
pi@moode:~ $

Regards,
Kent