Chosen Solution
Swapped i6 battery and got no results. Went back to old battery, all is well.
There are two possibilities here: Your battery may be fully depleted. Most vendors will ship the battery with a low charge state for safety reasons. It is possible that your replacement battery is simply “uncharged” and needs to be fully charged. Connect your phone to a quality charger and let it charge for several hours to see if that makes a difference.You may have received a defective battery. You’ll need to check with the vendor to see what the warranty/refund is.
I had exactly the same problem. Found that the battery connector was not seating all the way in because the bend was too close to the contacts. I carefully straightened the connector and connected the battery before setting the battery in place, then slid the connector cable in between the battery and case. Works perfectly now.
