Welcome to T-Mobile and thanks for joining the community! I am sorry to hear that your new phone is already acting up on you I know it has been a few days since you posted this but I wanted to check in with you to see if you were still having this problem? If so, where specifically did you get this phone? Also, did the phone already come with Android 7 on it or was this something that you were prompted to install after you pulled the phone out of the box?
Welcome, lt_ulquiorra! I just wanted to touch base and see if you were still having trouble with your new phone. How is everything going? We want your experience after switching to be stellar - please let us know if you still need help!