machinogodzilla, thanks for the kind reply.
Downgrading the firmware:
I don't know how to do that. Suggestions or help are warmly welcomed.
I tried erasing the internal memory via the Settings > Systems > Storage (along with erasal of the SD card, although that apparently didn't work, the books on that are still there). The stylus stubbornly continues not to work.
As of now, the "Build number" remains 2014-07-01_22-17_1.6.0_c0d94aa. (The "Kernel version" is 3.0.35, also dating from "Jul 1").
I found no manual on the device (viewed from the PC, the folder "manual" was empty). Instead enquired about firmware downgrading in the M92 manual available on the
Onyx site, but sadly it doesn't say anything helpful about my stubborn stylus problem

.