problems after iPhone 5 T-mobile logic board swap

Hello. So I have a T-mobile Iphone 5 that I didn't know was T-mobile cause it was unlocked but one day the battery wouldn't take a charge. So I took it apart to replace the battery and in the process of removing the battery I severed the volume cable and must have damaged the screen flex cable cause the screen wouldn't turn on. I was board (I know stupid) and continued to take it apart getting all the way down to the chassis, got tired, didn't put it back together and went to bed. I never got around to putting it back together and forgot where all the screws went so I decided to buy a icloud locked Iphone 5 and put my logic board into the new iphone 5.

Everything went smoothly, got my logic board out and put it in the new iphone, turned it on and everything worked. I started to have some problems tho.. First the time and date on my iphone seems to be stuck after I lock the device and I have to keep it unlocked to have the time actually work. Second is my battery seems to be draining quite quickly and gets warm after a while of screen on time. I've looked into the battery problems and everything points to the U2 IC which also means if it is that chip my locgic board is kinda screwed. And third is my bluetooth won't turn on it just shows the spinning icon like its loading.

After everything was put back together I decided to check the imei of the Icloud locked iphone to just see if it was blacklisted and found it to be clean but also a sprint device not AT&T like the guy said... that intrigued me to check my working iphone's imei and that i found that it was T-mobile not AT&T like the person I bought it from said. I haven't had any signal issues only the battery, time and date, and the bluetooth.

Any help would be greatly appreciated. thank you!