It is actually very common for the charging port to go bad. The ports are soldered to the logic boards and the cord tends to work them loose. The less expensive tablets seem to be especially prone to having this problem.
Insufficient strength in the solder joint is usually the culprit. You may be able to find someone to repair it, but it is normally cheaper to replace the tablet. I have actually advised several people to buy new tablets rather than have me fix them.
Good luck.