3.6V = nominal rating of Li-Ion cell and would agree with 25W/6930 mAH battery notation. Actual cell voltage can vary from 4.2 V to 2.6V, though cut off may be around 3 V. Agree 3.8 V stamp doesn't fit.
No moving parts, but what makes the clicking noise when you wake the ipad up or put it to sleep. Sounds like heads being parked, but that can't be the case with solid state drives.