Doesn't seem to be the problem I tried it. D :(

-My mistake I accidently posted twice.-

Sumo-Santa, The only other thing I can think of is because the upgrade tool does a basic compatibility check and compares the firmware you are upgrading to the firmware on the player already. If it detects that the firmware on your player is a radically different to the upgrade it will generate an invalid warning as well.
By disconnecting your player before the last upgrade had completed you may have corrupted your firmware and so the tool is comparing the two and finding a problem.
If this is the case your other option is to reset your chip as layed out in the Dead Player Recovery Guide HERE have a good read through it so you understand the process and what is needed to recover your player. You have a very good chance of a full recovery because you have a backup of your original firmware, but as you know any upgrade is risky and if there is a problem with your backup then you will have to track down another compatible firmware for your player.
When I wrote the guide I had to kill the player on purpose to work through the process and beleive it or not I had a lot of trouble killing it completely. In the end I basically did what you have done and disconnected the player halfway through an upgrade which did the trick.

My memory doesn't come out of my player. So is their any other way to upgrade the firmware on my mp4 without using The MP3 Player Upgrade Tool?