my s7 edge wont stay turned on for more than 5 seconds

-I bought this s7 edge, and the battery started to go cranky. the battery percentage fluctuates, and whilst charging it goes up and down. I'm using fast charging and said it would take 3 hours to go from 64% to 100%, also when I restart the phone the percentage changes massively.
- The second problem started from when I dropped it the other day, I had a case on, and was dropped on carpet. But when I shook it turned off, you can hear that some thing inside is moving about when you shake it, this problem has now developed and I charged it to 100% and now when I turn it on it shuts off when it gets about half way turned on, also this will only happen when it is charging, there is no response when its not charging.

I have tried to hold it in different positions when turning it on, I have also tried reseting on it, but it doesn't stay on long enough to attempt that....if anyone has any suggestions to resolve this I would very much appreciate it, thanks.