cater
i had this problem about a year ago and gave up in the end but will give you the benefit of my experience for what its worth
basically your firmware is corrupt and you now need to reinstall your firmware
your first problem is to id your firmware you may need to open up your mp4 player to find pcb board numbers, screen numbers,memory chip type then download firmware to the mp4
your second problem is you need to force your mp4 in to recovery mode by shorting out pins on the memory chip this will allow a program like mp3 player utilities 4.15 to upgrade your firmware
I used a site h**p//www. mympxplayer.org that was really useful with some good tuts
firmware will be in form wilson 9.1.52 or similar
saying this I never managed to fix the two I had they had hourglass on, in the end powering on
just white screen after many firmwares tried
hope this points you in the right direction
thanks turny