Where is the "Factory Reset" data stored?

Hi - Any searches I do for this just engulf me with "How to perform a factory reset.........

I'm asking because I'm guessing that it's hidden/encrypted, but after performing the FR on my Innnos D6000 - Chinese version, I am now stuck with a Chinese UI.

I've tried to flash SuperSu.zip and installed permanent TWRP. Then used it to install the ROM which I had previously successfully installed as an update from the SD Card.

This appeared to work - TWRP showed: - "No MD5 file found, Patching system image unconditionally, patching fimware images, Script succeeded: result was [t].........Update partition details.......Done" and the "Successful" message at the top of the TWRP screen.

When I rebooted however it was back to the same Chinese UI - Have since re-tried after wiping everything and even after getting the "No O/S installed" msg, phone still boots to same Chinese UI. (Am assuming that this is stored on the ROM somewhere and hidden or protected?).

Any advice on how to escape from this Chinese stranglehold and save what little is left of my sanity will be extremely appreciated - obviously I am a total Android newbie when it comes to flashing rom's etc!

Thanks to anyone for any useful info/suggestions!