Need firmware for sPMP 3050
 

I'm looking for firmware for my PMP3050 made by Sunplus.
ID of its board is: AJ250_V4 ; camera's ID: ST7680 0810
I tried downloading many firmware files, but I can't check do they work, because when I'm connecting my PMP by USB cable (even when I'm holding A+OK, or other key combinations like Down+OK), the "Found new hardware" information doesn't show. What should I do to upgrade my firmware (its version is V4.01.081017) ? I can't play games other than NES and listen to radio :(
Please, help me...

I'm refreshing the thread - can somebody help me? :(