If you are certain you reset the unit, there is no amount of tweaking that would shut AWM2 off through a reset. You should have the instrument looked at by an Authorized Service Center. Contact Yamaha for the Service Centers in your area.
Sorry you are having an issue...

Hi Christoph
When i first loaded OS2.5 my AWM2 engine was only able to play some sine waves on every preset. ( i didn't check what FM was up to, i was too busy panicking).
This was cured on my machine by reloading OS 2.5. Is this what you experienced?
Graham

Thanks, i already contacted my Dealer.
One Question: How do i perform a reset?
Is a reset done by updating the Firmware? And will this be done by „updating“ from 2.5 to 2.5?
Tranks again for your Support, i keep you informed..
Regards
Chris

There is a button in the Utilty -> System area which also to initialize everything. That might help.

Thanks.
I did this Twice. If That is the reset, then my Montage has an issue..:(

Yes, I would agree. I guess it is some repair center for it as BM also proposed. Sad but happens.

The "Initialize All" feature is not the same as re-installing firmware. Since this seemed to work for someone else - it may be something to try. Installing the same version over your current one should do no harm assuming you have everything on the instrument (user content) backed up -- as you must have if you're already doing full factory inits.