Well, tried installing dsmid's images twice, based on the instructions here:
https://wiki.mobileread.com/wiki/K3noobdebrickatk
I'm using FSL_ATK_TOOL_STD_1_67.
I also use mmblk0p1-3.4+jb+keys+physkeyb.img and main_kernel-3.4.img, renamed as rootfs.bin and kernel.bin
Everything goes OK, except for step 18: Unplug and reboot your Kindle.
Once I unplug the Kindle and press the power switch momentarily I get no reaction, even after a couple of minutes. I have to hold it down for 30s or more to get it to revive. However when I do that, it boots up, but the keys w,x,a,d and s don't move the cursor.
The file keyboard.txt is in there, though. Am I doing something wrong?