Well, I've managed to flash it with MP-683EGCF-MV1.bin
everything seems to be working fine, but the problem is, device is detected as mass storage device, but no files can be written to it - says it's write protected! BUT! It can be formated with own formatting utility! and became 512MB!
So, what I have:
Partially working player - seems like to be ok, but no files can be written to it. Nor from computer, nor from internal voice recorder (says Disk write error)
Own formating utility works, but it formats it to 512mb, and after formating, files are still unwritable...