Try contacting the Samsung technical service section in your location (country even) and asking, as there is none available online, whether they have the firmware for your particular model available and could you either purchase it or get it somehow, so that you can re-install the firmware using a USB flash drive. (This approach worked for me with my TEAC TV which had the problem of powering on with no picture or sound problem. There was no firmware available online but tech support emailed it to me.
It never hurts to ask, the worst that they can say is no.
I found this while reading the guide for your TV and while it will probably do nothing it never hurts to try.
''Problem : The ‘Resets all settings to the default values.’ message appears.
Solution : This appears when you press and hold the EXIT button for a while. The product settings are reset to the factory defaults.''
So I was thinking that perhaps you could try holding the exit button on the remote for a while, 30 seconds say and see if anything happens. Worst case is that you have just wasted 30 seconds of time.