Have you checked the contacts from inside the port. Last summer I once used low quality cable to connect my N900 to car charger and the connector actually short circuited and some of the plastic from the connector melted over the connection pins in n900 so it would not get contact until I scraped the plastic of with a bent sewing needle. After that it worked quite fine until last week when I again somehow decided to use low quality cable and ripped the whole port of. Now I'm waiting for replacement from KLC to arrive tomorrow.