samsung galaxy mega 2

I've had my Samsung Mega 2 for 2 years. My question is can a phone cause reception problems? Lately I've been having problems with only having 2 to 3 bars and when I talk to someone on the phone they say I sound garbled and then they can't hear me at all. Is it my phone or can it be something...

ok I have a Galaxy mega 2 I tried rooting it and it bricked it bad! Sent it to Samsung and they seen it was rooted so no help there took it to a cell phone shop and it won't connect to odian if that's spelled right lol and won't recognize it so how can I get the software back to the original...

Now that there is a root available for the Mega 2, I need help finding a ROM for this device. SM-G750A Link for root: http://www.kingroot.net/down it is Chinese and I have no clue what any of that means, but it does work, and I have verified the root.