Just put a fresh Samsung in 2100 mah wonder if that could be the issue I know that Yihi recommends 2500 mah
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True, don't do it! They say it will be out before the end of the month but it has not yet been posted.I don't think the software and firmware update for the M class has been issued yet (could be wrong--I know it's due out soon). If you use the ones for the S I think you can brick your device. I'd recommend that you wait/read before trying anything with the firmware on the M class so you're sure not to make a mistake.
btw... I love the gravity sensor but when switching menu options you need to be sure the unit is upright otherwise you will be using the gravity sensor to select your choices unknowingly. If you get used to doing that you might like it but the new release supposed to be able to disable the gravity sensor.