CarolineM , The link below is a partial tear down to get inside the device to access the charge port. Repairing a loose USB type charge port that is soldered to the mother board is a delicate procedure and when not experienced while fixing could cause more damage to surrounding circuitry because of heat necessary to install new port or to reattach old port. Changing charge port,normally not a job for the beginner. 2nd link below is a video just to show what is involved in replacing, The guy makes it look easy but believe me it is not that easy and if going to attempt work very carefully and do not rush. If not comfortable doing repair have a good local computer repair shop have a look and estimate cost of repair. Good luck.
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Asus Chromebook C201 Motherboard Replacement