Many thanks. Will go through all the posts again to make sure I do it properly. Just trying to find the idiots guide and step by step instructions.
There is not available OTA updates for the custom ROMS (or at least the ROMS that i already tested), only with the official MINIX firmware (non rooted).
To revert from custom firmware to MINIX firmware you need to flash the device again.
Instructions here - manual installation: