Yep, I tried to reset using F6. That was actually my first attempt at a fix. I also tried to load the default values through the menu.
Are you absolutely positive that you cleared the FRAM correctly with F6 during bootup? In other words, ALL of the previously saved settings (channels, image hardware, etc) were gone? If not - make sure you're certain before going further - for example, set something specifically, then clear the FRAM at bootup.
There is also 'Security Clear'- it will clear both the FRAM
and NOR FLASH - which contains 'Firmware, Bin, Internal saving' (according to Rigol doc). The problem is, I don't know if it clears the bootloader or other vital data (calibration settings, model and serial number, etc) - but it might - which could leave you with a bricked DSO. So I strongly advise you should check with a Rigol representative/dealer before attempting it. If you're still sure you want to try it - I can post or PM you the method.