dial *#0011# and check which band your network is connected to.if you're using jio and Connected to band 5 than you've to change it to band 40.check if its need to be changed then i'll tell you how to change this band if you want.
wait for 2 or 3 days you will see battery usage. it is showing Learning usage pattern because you recently reset your device and your device now Learning how much you use your mobile.
i am facing this problem since February update. i did almost everything, factory reset, visited service centre many times but nothing changed. This problem is persistsing in the update which Samsung is not solving.
