Flashing the firmware is changing the software on your mp4's hardware. Just like windows on your PC. In 99 % of the cases this will kill your player. Just like installing Mac OS X on your PC, dont try this.
And this may solve your problem:
http://www.mympxplayer.org/a-questio...rf-vt5474.html
If you succesfully connected it to the PC using the Dead Recovery Guide and this, proceed using the format tool to remove the memory hack.