When there happens a failure message (or no at all but no booting-process), try to overwrite your files a second time, try to re-download your file (eg "crc miscompare"), try to reformat your usb-stick (eg "is not a multiple of the nand erase block size"), try googling...
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When there happens a failure message (or no at all but no booting-process), try to overwrite your files a second time, try to re-download your file (eg "crc miscompare"), try to reformat your usb-stick (eg "is not a multiple of the nand erase block size"), try googling... (one time it helped to remove batteries for approximately 10 seconds. There are anecdotal cases where this resets the electronic controller that has unhung.)