Okay turns out I had successfully flashed it over the too new version using the SD card method, and the problem was I did not configure the serial port id into klipper ( I assume this is usually done in the background by RatOS configurator, so I added the section into my printer config ( overridding RatOS, reset all, and it booted us with same version numbers ) !! Yay, and off i go to initial tests.
[mcu]
ls -l /dev/serial/by-id/*
serial: /dev/serial/by-id/usb-Klipper_stm32f446xx_btt-octopus-pro-446-if00