Hi Everyone! Couple of weeks ago I noticed that my iphone 6s won't charged to 100%. The battery indicator stucks at around 77%. I updated to ios 9.3. but it didn't help. Last time I plugged it in at 30% for the whole night, but in the morning the charging indicator was at 77%. Other occasions I noticed that when I disconnect the phone from charging, the indicator would update like 2 or 3% without plugged in. What shall I do about it? Any advice would be much appreciated!