Kobo constantly crashes back to Reading menu

[avalanches]

My original Kobo was working great until one day the screen abruptly developed a fault. To Kobo's credit, they arranged to have it couriered and shipped a replacement before the return unit had even reached them. Magic!

However.

The replacement unit is totally faulty. Every few minutes while reading, it randomly dumps me back to the "I'm Reading" menu.

I'm pretty sure they sent me a refurb unit since it has some scuffs/marks on the screen. Too bad they didn't FIX it first. I can't find anyone experiencing a similar issue and thus no way to fix it myself. No amount of resyncing, resetting or swearing has solved it.

I even can't return it to Kobo anymore because I've since moved to a country that their customer service doesn't support (Japan). At this point I'm over it and ready to jump ship to Kindle -- who do, incidentally, provide customer support in Japan.

Has anyone ever heard of this problem before?