My iPhone turns on to flickering apple logo

I got the phone from someone else and basically, the problem is that when I plug this phone into the charger it turns on to a flickering apple logo that goes up and down vertically. It does there peridodically and there is a little smudge on the bottom of the screen. I was told it was an LCD issue but I wonder if it has something to do with the logic board. It suffers a lot of cosmetic wear I am guessing it was dropped a few times. I checked the liquid indicator and there was only a white line so now I dont even know for sure what is wrong with this thing. I hope that it is just an LCD issue and not a broken logic board. I'd appreciate all the help I can get.