Wago 750-833 flash memory reset

I have a 750-833 Profibus programmable fieldbus controller from Wago that I would like to implement as a fieldbus coupler.
To do so, the manual states that the controller must be "empty".
Right now a program is in the flash memory and my problem is how to erase this?
It was suggested to do a firmware download to the module but I have not found any firmware files on the Wago homepage for this.
Calling Wago (Germany) they told me to download an empty program containing only a semi-colon [;], flash this and put the controller in stop-mode.
But again this does not work.
Any suggestions would be appreciated.

Try to set operating mode switch in fileldbus coupler in the middle position, boot project would not start aftre power up. Then power cycle coupler. Maybe this helps.
If not, send me your e-mail then I'll send you software for writing coupler firmware.