RTFC == Read the Frelling Code.
As it turns out, I'm wrong about the r= stuff, and there may actually be something wrong with your board.
There are two possible r= codes: nfx and npwm
nfx == No File_eXists, meaning that the currently logged in user's profile is missing.
npwm == No PassWord Match, meaning that the user password check failed. That's the one you're getting.
I suggest hitting the clearcookies page a few times in a row, then logging in and trying the request again...
