I have a B008A (firmware 515460094)
~help works but not exec.
on mine ~memInfo and ~changeLocale give result too..
but I can't figure how to get result with ~exec
I also tried things from this page : http://igorsk.blogspot.com/
which works, and dump current debug log into the "documents" directory (I will read the dumpMessages more carefully)
I tried ~terminal too.. but the kindle reboot after that
by the way a shortcut for ~help is ~h
(something unrelated.. alt-shift . display some barcode of the kindle)..