HUGE stamina mode issue

[HarryXI]

My Sony X is 2 months old and after I updated it to Android 7. My stamina mode only gives me 2hrs +!!!!
On marshmallow, my battery could last the 48hrs ... Now at fully charged with stamina mode, it can last only a dalf and a few hours.
I NEVER charge my phone over night,
When my phone get's hot I never over work it
I simply updated my software and stamina mode is BROKEN, . Even my battery now feels like it's degrading....
Please help or I'll have to send this back and get a new phone.
I'll need reasons for why I need a replacement, so please help me

[_alexdon_ · Accepted solution]

@HarryXI That is just an estimation and is not accurate after a software update. Try to reset the stamina estimation by doing this: go to settings - apps, tap on the 3 dots and show system. Look for stamina mode, tap on it, under storage tab clear data and force stop the app. Restart your device.