Originally Posted by lporter
I have a question - If I have access to the serial port, is my kindle basically unbrickable? I ask this because I am doing all sorts of flashing to try to get android to boot and I don't want to toast my device.
Bootloader (U-Boot) is written on separate boot partition. It's not a partition defined in the MBR, it's a bit "low-level", hardware-defined eMMC partition. It's not accessible from stock Kindle Linux, but it's recognized in recent kernels. It could be overwritten from fastboot mode, though. My investigations on this subject are here
It means that with access to serial port you can completely erase /dev/mmcblk0 and still have no worries: just get to U-Boot prompt through serial connection, enable fastboot mode, flash MBR, diags kernel and diags partition with SSH, load diags, SSH to it and dd
main partition image to it's partition. (OK, maybe you'll should worry a little
, because I didn't try this scenario, but I honestly don't see any problems there.)
However, if you'll somehow erase that boot partition (and, therefore, delete U-Boot), you'll be out of luck, because there will be nothing to answer to serial connection.