Sorry, can't help you with the VX file... You can buy the already programmed chip from here:
That is my trusted source (BIOSDEPOT). I bought the VW chip from them and it worked.
Hope it helps.
The two possible problems that might have occurred, in my opinion, is that either you did not solder back the chip correctly or damaged the chip, or the second and most probable, the method that you used to flash the new bios was in some way not correct. I once failed to flash a bios directly to a chip, you need to have the right tools and everything must line up bit by bit into the chip. If there is an error of just one bit the thing wont work.
How did you remove your chip ? How did you reflash the bios ?