karloz25 , as gaboon mentioned, your player can be themed. However, the firmware cannot be upgraded, and is never recommended to upgrade.
If you want to theme the player, always use your own extracted firmware to theme, and then re-flash it back to the player.
Extract and repair your firmware, guide here
http://www.mympxplayer.org/how-to-ex...tool-vt66.html
Theme your extracted firmware using S1res, guide here
http://www.mympxplayer.org/how-to-mo...ool-vt206.html
There are many themes that you can use from the downloads section. You'll need to manually change each image with the images from the themepacks, same for text strings.
When done, you can re-flash the themed firmware back to the player, guide here
http://www.mympxplayer.org/how-to-up...ayer-vt46.html