I can't help if your only message is, it doesn't work.
Please clarify your steps. What kind of usb device are you using ?
My box has both a 500G hdd and 2G usb disk and they work fine.
/dev/sda1 on /media/hdd type ext4 (rw,relatime,barrier=1,data=ordered)
/dev/sdb1 on /media/usb type ext4 (rw,relatime,barrier=1,data=ordered)
Initialisation of a storage device takes some time.
I did not test the initialization menu's, because my disks are already in an working format.
If you are using devices which are in fat or xfat format it can cause problems, i would go for a ext4 formated disk.
Try to completely erase the usb first to get rid of already existing partition tables.
Also storage devices are the first to fail when you powersupply is bad (blown capacitors).
i am using san disk cruzer 2gb open atv 6.2, 6.1 verzion, is ok mount no problemes but this 6.3 no mount usb go to 99% and stop give me this mesage :
initializing storage device ...
Error: Timeout elapsed, sorry
i no have problem with capacitors open atv 6.2 works well usb