Not sure it's a defective behaviour but it seems to me the power button's functionalities are a bit borked.
In the user manual it says 2 secs push to turn it on, just a quick press for standby and a prolonged one to switch it off.
Well to me it's more like standby and power off cycle themselves with no chance to go one way or the other according to press lenght. Basically: I'm reading, I press pow button for *a while* (way more than 2 secs) and it goes into standby, then I switch it back on, I keep reading, I push pow button again for few secs, it switches off. Next time, it'll go into standby, time afer that it'll switch off..... short press simply does nothing. Is it normal?