It could be the charging port or it could be something else on the motherboard. Almost the same thing happened on my SGS GT-i9000. I couldn't turn it on, and when I plugged it in, I got only an empty battery with a circle showing up . I couldn't make it boot. So I took it to a GSM service and the guy there said that some connections on the motherboard were fried and the charging port was damaged, so I left the phone to him and 2 days later I got it back repaired for 20 Euros. I recommend you take it to a service, or if your got the know-how, replace the charging port(very cheap), hopefully it will be fixed.
Asus Google Nexus 7 2013 16GB (WiFi)
LiquidSmooth 3.2 -> 15/09/2014 Nightly
All Volumes Booster Mod:
Samsung Galaxy S GT-I9000 8GB MoviNAND
Mackay ROM 4.9.11
Mackay Kernel 0.691
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