radarshop , it is not possible to identify which firmware would work properly with your player as there is no proper versions control with the player manufacturers. So basically you'll need to try all the available v3.5.37 firmwares until you hit the right working one.
It's not an easy task, but that's often the only way to recover a dead player.
v3.5.37 firmwares here
http://www.mympxplayer.org/actions-3537-dc16.html
And also try the v3.5.35 firmwares if all the v3.5.37 do not work. List here
http://www.mympxplayer.org/actions-3535-dc15.html