I am not familiar with the DX machine.
I do not know what you have done that got you into whatever situation you are in.
I do not know where you can get recovery images for a DX machine.
It should be obvious from the title that: 4. Erase MMC0
Is not going to improve your current situation.
Once you do that, if it does what it says, then the only firmware on the machine will be the iROM code (a very low level firmware loading command processor).
The Freescale ATK can still "talk" to your DX once you do that. So could the K3Flasher if you modified the code to include the i.MX31 related things rather than the i.MX35 stuff for the K3.
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Try looking for th edit button again, after you have made a few more posts. I think the system has a minimum of ten posts required before it turns on the edit button for a person.