Unable to factory reset gt-s5830i
Reading your question a second time, I just see you're on the complete wrong track (a thing we call the XY problem):


  Now for many reasons I would like to factory reset my device to it's original ROM


That's not possible at all. You overwrote this when flashing MIUI (for details, see our factory-reset tag-wiki). You'll have to get yourself a ROM file to flash (see: Where can I find stock or custom ROMs for my Android device?), and flash your device again if you want to "return to stock".

That said, it makes no sense to get your "supposed solution" to work – as even if we did, it would not solve your issue.