I need some guidance from the experts here. I've read a ton of stuff and tried various things but no lock. I have kindle with FFF 1.4a and TWRP setup. Somehow the SD drive volume is corrupted so I can't load any image (original kindle or twa) to update it. I can't get into adb shell so I can't fix the bad sd volume. however I can get into the bootloader using the usb port and run fastboot. I just need to know how to reflash everything from scratch in the fastboot to get the original kindle, or flash updated TWRP and a good rom.
I have read everywhere but can't see what commands to issue in fastboot to wipe/load the image. I also tried the unbrick utility but no luck. The simple thing I would think would be to fastboot load the full amazon original rom, overwrite everything and then stat over with KFU. I just don't know if I need to replace the boot, the loader, the recovery part, or all of it, and how. If the experts here can give me some guidance and what commands to issue, I would be greatful.