It definitely sounds like the battery cannot charge past this point anymore. Has it ever been dropped with the cable plugged in to the port? If yes then it's possible to solder has been broken on the board.. Although the system detects power so I'm thinking it's battery at this point.
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=== Update (11/16/2017) ===
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When you connect the tablet to the pc do you see the Charging/USB options appear at the top of the notification [image|1262780][image|1262779].. try selecting the charging only option and see what happens. The PC might also not be outputting proper voltage from the port.
It definitely sounds like the battery cannot charge past this point anymore. Has it ever been dropped with the cable plugged in to the port? If yes then it's possible to solder has been broken on the board.. Although the system detects power so I'm thinking it's battery at this point.