By the way, the battery drain seemed solved (except if a battery duration of 5h30mn in web surfing is not normal for the ME301T ).
But to be exhaustive, the factory reset didn't solve the "Battery usage data not available". Do ME301T owners got this message in the battery info or am I the only one ?
Perhaps the firmware upgrade to 4.2 could solve this problem but I prefer to stay with 4.1.1 as I'm scared of the different upgrade problems I've read (bluetooth, battery drain, ...). Did you all upgrade to 4.2 flawlessly and without noticing side effects afterwards ?