- reinstalled PRS+ Zork;
- fully-charged the battery;
- re-tested text memo + handwriting (both as "standalone" and "bookmark"): the behaviour of the sony hasn't changed. It still powers itself off whenever i go near memos and handwriting (now even deleting a memo or handwritten sketch causes the sony to power itself off).
why would it do that all of a sudden? I'll now try and format it and see what happens.