Originally Posted by laime
Is Kindle Touch 3G c firmware 5.1.0. I want change firmware to 5.0.*. In MfgTool chose "Kindle fastboot", in fastboot mode, flashed mmcblk0p2 to version 5.1.0 with SSH, and put boot into diag "fastboot setvar bootmode diags" and "fastboot reboot", after reboot appears tree with boy. I tried load diag mode in MfgTool, but it does not work. If choose in MfgTool "kindle main" to loaded main menu Kindle. Battery is fully charged. Diags menu don't work.
You may have mismatched diags partition and kernel versions. Try flashing 5.1.0 diags_kernel.
EDIT: I do not see a 5.1.0 diags kernel, so flash 5.0.0 diags and 5.0.0 diags_kernel instead. See if that works. This is the way most successful debricking reports said they did it. You can always flash old firmware, then do an official update to new firmware.