Thank you,
sndestroy.
I withdrew the board (prevented small screws under the speaker).
S/N: QY-14C2-STLS 2006.05.20
I have found here:
http://mympxplayer.org/firmware-pma-300010-df385.html
But RdiskUpdate written:
Error / Invalid upgrade firmware file!
My player with FM-radio and 3.7 V battery - perhaps because of this?