Adriean, In the name of science last night I purposely set out to kill my player with a bad firmware upgrade. It was not an easy task after trying 6 versions of firmware that were not accepted by my player I finally managed to do it because the upgrade program crashed leaving my player with a black screen and no PC connection.
I do not know if it will help in your case but this is how I recovered my player which had a black screen, would not connect with my computer and continually turned itself on and off when plugged into the USB.
First I opened the player then turned it on and connected it to the computer, then using this post by arish_06
http://www.mympxplayer.com/viewtopic...=asc&&start=30
I shorted the memory chip with a pair of tweezers. The player was immediatly recognized by Windows as an ADFU device and it installed the drivers for this.
Then I opened the MP3 Upgrade tool that told me that the player was in repair mode and asked me to select a firmware file.
Note: If you have a backup of your firmware at this stage it is no good to you as it is not a complete firmware file and will give you an error message when you try to install it. You need to find a full version firmware. It may not have to be the same version as your original. My original was 3.5.35 and I used 3.5.37 to recover.
This is the one I used
http://www.mympxplayer.com/dload.php...6364da93f003b1
Although it is not the right version for my player it is a full firmware and did install on my player. I then switched the player off for a few seconds and then back on. Although the player was not yet in a working state I was now in a position to update with my backup firmware dump.bin.
Here:
http://www.mympxplayer.com/dload.php...le&file_id=186
After doing so the player rebooted and was back to it's original state.
The hardest task is to find the firmware files you need. Files ending in .fw instead of .bin are more likley to be full version firmware. I suggest you download a selection of files before starting so that you have a few to choose from. Some of you may be reluctant to short your chip for fear of destroying it completely which is a possibility but if your player is not connecting with your pc and you can not upload firmware to it I do not see that you have much choice. A brain dead player is not much different than stone dead one.
I may have been lucky, but I hope this will help.