Zest, Did this happen backing up your firmware or trying to upgrade it?
Basically you have not found the right firmware for your player. There are so many variations now that finding the right one will just be trial and error.
Try contacting the seller and asking him to send you the firmware, and check the mini disc that came with the player occasionally it has a copy but it is rare.
As long as it is still being recognised by the upgrade utility you can keep flashing, once it stops you are going to need to open the player and short the memory chip to reset it. The DEADS PLAYER RECOVERY GUIDE outlines the procedure.
HERE
Once it dies it becomes twice as hard because you then need to find a working combination of Full Version firmware and dump firmware to restore your player.
Sorry there is no quick fix for this if you have no luck with the firmware on site there are others at
www.s1mp3.org. New ones are also uploaded here most days.
Good Luck and keep us posted of your progress.