Hi Gilles,
Well your nano clone looks the same as mine, and the firmware you downloaded looks to be right as it worked for me, but i know these things can look the same and yet have different components inside.
One suggestion is try updating again but with a different version upgrade tool, I had problems with the one that came with my player but had more luck with version 3.68 or 4.00 both of which can be downloaded in tools section .
http://www.mympxplayer.com/dload.php...r=DESC&start=0
Good Luck.
Terry