In order to go mainline klipper on the SV08 you should have an STLink V2 usb flasher, because you have to flash Katapult bootloader on both mainboard and toolhead in order to flash the Mainlin klipper build on them. If so you can just try to flash the stock bootloader and klipper build that you can find on the SV08 Mainline Klipper GitHub, there is a section dedicated to the backup files.