Many thanks for the reply! The raw values where from some of the HRM monitor apps, not me reading them from the event.
I'm attaching a 1 min file that I just recorded with the HRM Data Exporter app, while my arm was resting on a table and trying to keep it as calm as possible. It's not -2, 100, has a bit more values, but still saturated data that doesn't look quite appropriate.
Importantly, I'm almost totally sure that I'm still alive and that I have a pulse, will ask around just to be sure.
Do you have any ideas about what could be happening?