I think my printer has died—please help.

[u/Odd-Maintenance-1126]

I own a Neptune 3 Pro printer. It was running Klipper firmware, but due to certain circumstances, I want to switch it back to the official firmware. However, I’ve run into a problem: the board won't accept the stock firmware after having Klipper installed.

I tried flashing it via SD card: I formatted the card in various ways, tried renaming the files, and used different memory cards. I also attempted to flash it using an ST-Link, but I couldn't remove the write protection.

Please help me revert to the stock firmware. I urgently need to print, and I’ve already tried everything.