You, you don't have to return it.
I spended my whole day today with this Problem. I have a german MDA Compact IV.
And I produced the same problem, that you have.
My problem was, that I connected the MDA IV to a Computer in my Company. This Computers have a HDD-Encryption from Safeguard.
After connectin it, the NAND-Storage was gone. There was no possibility in getting it back, as described here.
I (and you too, for sure) know, that there is a way to get this device back to the factory defaults, by typing on "settings-->System-->Erase Memory (hope, this is the right translation, since I use a german device).
Here you come to a drop down menu. And can select "format internal storage". Then you get the error message: No NAND device found.
Had the same problem.....
The ONLY solution for this:
While the device is turned on:
Remove the Backplate and pull out the pen.
* Press "Volume down" and "Enter" at the same time.
* HOLD this two buttons pressed down, while you use the pen to press the red "Soft-Reset-Button".
* release the red Button an keep the other two buttons pressed. I know, it's a bit tricky to get this realized.
* You will see the display changing to "rainbow-colours" for a short moment. When this happens, you can release the two buttons ("Volume down" and "Enter").
* After that you get a grey screen with blue fonts on it.
* No comes the interesting part:
* If you press "Volume up", you get a factory reset, WITHOUT any changes beeing made at the NAND
* If you press "Volume down", you get a factory reset, WITH erasing the NAND and new formatting it.
* After two "progress bars" in blue colour, you will be asked to push the "Volume up" button for Booting the device.
Thats it !!!
Wait and wonder, that your NAND will be back in place
Too sad, that noone from the Hotliners, can tell this ti the customers....
Hope I gave you this answer BEFORE you sent in your device.
Greetings from Cologne,