vinciii, The firmware you have loaded is not compatible with your player. It was most likely designed for a different LCD panel. There are 100's and 100's of variations in firmware and no way of easily telling which ones will work on which player. If you do not have a backup of your original firmware you will need to try some others till you find a better match. Be warned though that the problem could get a lot worse before it gets better. Your player may stop responding completely and no longer be detected by Windows or the update tool. If this happens you will have to use the Dead Player Recovery Guide to reset your player.
One thing you could try is loading the firmware into Firmware Modifier which has a setting for increasing screen contrast. You can download it here:
http://www.mympxplayer.org/firmware-modifier-df17.html