Most of what applies to a Nano and NX are interchangeable, but is this NX or Nano?
A far more important question: Is this a production module (which uses eMMC), or is this a dev kit module (which uses a microSD card)?
The flash command you gave is for a module with internal eMMC, and not the microSD. If this allowed flash, but the unit is really a microSD card module, then it isn’t surprising to see block device I/O failure…since there is no eMMC on the microSD model.