I have just fixed mine and it took about 5 seconds, really! I had all the same issues mentioned by others. Slow charging leading to not charging at all. Or it charges for about 1 minute then cuts off. I blamed the battery, then tried another. Same problem. I blamed the port connector for being loose as when I wriggled it then sometimes a charge would kick in for a short while. I blamed the charging lead because it was too thin or the wrong type, I blamed the plug that the charging lead goes into. IT WAS NONE OF THESE (well not quite)
I figured it might have been the connectors from the charging port to the mother board because so many 'experts' had suggested getting it professionally fixed. It was not the problem.
I solved it / fixed it almost by accident but also because of what several people wrote about fluff and dust and dirt getting into the charging port and how they fixed it by using some sort of spirit to clean it out or in one case a small pin. I live in San Pedro Belize which is a salty, sandy island by the way.
THE SOLUTION? Simple! I purchased an electronics duster called 'Dust off' (Incidentally, I am not an agent or in any way connected to the product, I'm sure there must be several other brands out there) it is a small aerosol canister that has compressed air (I suspect some sort of alcohol or spirit too from the smell) but it is dry air that comes out. The cannister comes with a small straw attachment. I squirted this into my charging port for about 5 seconds. My phone charged up immediately on my cheapo charging lead - not even the more expensive one that I bought. Took about 2 hours to go from dead to 100%. The phone now charges like new. Give it a go, it's super cheap and super fast. Best wishes, Vic