I am super sorry to hear that you are having issues with your battery on your phone. It sounds like you have done most of the troubleshooting that we would normally recommend. If you have insurance on your line, you would have the extended warranty and we can look into your replacement options.
I had the same issue and received a replacement phone and had the same issue. I charged it ALL NIGHT and had 40% in the morning. It can be fixed, t-mobile is not the carrier they used to be.
I am so sorry your replacement is doing the same thing magenta6148180. Are you using the same charge you did with your first device? It might be worth trying a different charger to see if the issue persists.
bennybean: this issue started when Oreo was originally pushed in late May/ early June to the Galaxy S7. There are multiple forums discussing it. It is a widespread issue.
I am not sure why we would need to have an extended warranty for a software issue that was pushed by T-Mobile/ Android. AS mentioned above, this issue has been on multiple forums over the past several months. Note that if yo look at these forums, this is not specific to TMobile, but with all carriers. It is an issue with Oreo on the S7. It is a widespread known issue.
My Galaxy S7 was the best phone I have ever had up until the Oreo update. One day the phone worked great, the next it became slow with massive battery drain. I need to charge at least 2x a day now, and I am a light user. There is a lag when simply answering a phone call. There was another update 2 days ago that I hoped would fix the issue, but the battery is still draining fast. It is ridiculous to say that we need a warranty to fix a software issue that was forced upon the user.
I saw in another thread on the same topic (unfortunately that one is locked as I would have liked to reply to T-Mobile support on that chain: S7 Battery Drain With Oreo Update
Anyways, me and my wife have the same Samsung S7 phone (T-Mobile 930T 32GB Samsung S7 in Gold color unlocked). The only difference is the mobile apps we installed. In the other thread, T-Mobile support was thinking it was third party applications that was causing the issue and I tend to agree. It seems like my wife's phone is always needing to be plugged in where mine seems to be draining at a normal rate. We'll try to uninstall her apps one at a time until she doesn't have any app that I don't have (we both have Facebook, Whatsapp, etc so no need to remove those). I'll report back on that experiment and then she will slowly add the list of apps she uninstalled back onto her phone.
The other experiment I was thinking of trying was to uninstall and reinstall all of the apps she has that I don't have to see if that helps. I'll reply to this thread with the results. She's not too keen on this experiment since she uses her phone for everything, but hopefully we'll do it by this weekend (10/14/2018).
For now, here are the list of apps she has that I do not have:
AllTrails: Hiking, Running
Barcode Scanner Pro
J&J Official 7 Minute Workout
Jiff - Health Benefits
LINE: Free Calls & Messages
Ovia Pregnancy Tracker
Now, I remember I changed notifications on some apps that I have (and here is my full list of apps). Hopefully this helps with troubleshooting. Also of note, when I got my phone from eBay, I installed all patches and Android updates BEFORE installing any apps. So there are a few things people can try after they have backed up their data:
1. Factory reset and patch to latest Android OREO before installing any apps.
2. Uninstall apps they installed and reinstall to see if that helps.
Apps that begin with asterisk have notifications allowed.
Google Play Movies
Google Play Music
*Google Play Store
Music Folder Player Free
T-Mobile Name ID
The Weather Channel
I did more testing and it seems like the August 2018 patch is what killed our phones. For a while, I had been running the April 2018 patch (with OREO) with less issues than my wife's phone. With the August 2018 patch, I notice a few things that were'nt in the April 2018 patch:
1. Phone is SLOW
2. GPS signal is often lost while navigating and sometimes blue arrow doesn't move on the map
3. Battery drain
I'm in the process of a factory reset and I will list the patches installed to get back to April 2018. I didn't have my phone set to automatically install patches so I think I can leave my phone like this until they release something beyond August 2018 for us to try out. The good thing is most of our app info is in the cloud these days (with a few exceptions) so there wasn't much for me to backup before the factory reset. The other option for OREO problem users is to patch your phone before the huge 1.4GB patch for Oreo and just stay with the previous Android flavor. I'm of the belief that we can run OREO without the latest patch.
WARNING: This will wipe out all of your phone's data. Backup data not synced to the cloud (photos ,etc)
1. Download Samsung Odin 3.13.1: https://odindownload.com/download/#.W8IBN2hKiUk
2. Click the Download now link just beneath the text of 3.13.1 and above the text of 3.12.3.
3. On phone, click settings, about phone, software information, tap build number 7 times to enable developer mode.
4. Go out of settings and back into settings. Scroll to the bottom and select developer options.
5. Enable USB debugging.
6. Boot device into download mode. Power off phone. Press down, power, and home at the same time.
7. Press up to go into download mode (top text should say Odin Mode HIGH SPEED).
8. Visit the website below
9. Download samsung usb driver, install it.
10. We'll want the last version of Nougat for the T-Mobile SM-G930T phone (Samsung S7 for T-Mobile).
11. Clicking on that version should eventually lead to this link below.
12. Zip file will download.
13. Right click on the odin binary and select "run as administrator".
14. When you plug the USB cable into your phone, under the ID:COM field your phone should show up on a COM port. If it doesn't, the Samsung USB drivers did not install properly.
15. Extract the zip file of the ROM into its own folder.
16. Within Odin, select the BL file, AP file (this will take a while to load, it's over 4GB), CP file. For CSC, select the HOME_CSC file since this is also specified within the Odin application.
17. Once you click start, there is no turning back. If you want to turn back before this point, press volume down and power to exit download mode. DO NOT UNPLUG THE PHONE DURING THE FLASH PROCESS.
18. After you get the green pass in Odin, your phone will reboot. Most likely, you'll get a message about data corruption because you had Oreo files and Nougat is trying to boot. To get out of this, power off your phone.
19. Hold down volume up, home, and power.
20. Factory reset your phone and then restart the phone.
21. For the google two step notification, you may need to select more options and then choose the text with automatic authentication. Then, allow your device for authentication from Google.
22. Optionally, restore apps and data from your device (it may remember your previous phone, not current phone). I chose not to restore since all of my stuff is in the cloud.