I have flashed my Yamada 6700 3 times and each time the flash didnt seem to work. Here are the results:

It took me hours to find out how to check the firmware version on the player as its not documented in the manual. Seems like pressing 1, 3, 7, 9 brings this up.

1st Try:

I downloaded the official firmware version "2.0" from Yamada.de. I performed the upgrade successfully. When the DVD player restarted i checked the firmware and it still showed "V1" and not "V2". Appears the upgrade did nothing.

2nd try

Same result as above

3rd Try

Used firmware "Yamada6700_1257_V3_MHZ" from this site as official Yamada firmwares didnt do anything. Did the upgrade the same as the others. The DVD player Ejected the CD after doing the upgrade and the player restarted and it showed a blank screen and was dead.

Verdict

Now i am left with a dead player after performing the upgrade exactly to the specifications of Yamada and this website. Unlike most people on this site i dont have any electronics/electrical experience so dont have any idea how to knock up a serial cable to fix the player. Perhaps instructions could be written with photos for a complete electrical novice?.

The moral of the story. If your player isnt broken and works ok dont bother to try and flash it to the latest firmware not matter how tempted you are.