Hey the same thing has been happenin to me my tablet wouldnt charge everytime I would connect the charger it had a red 'x' over it nd it would only charge wen I would power it off but I would leave it for 3 hours nd it would only charge for about 10-20%
Heres how I fixed my problem
Nd hopfully it helps u guys out
Turn off ur tablet then press thepower button nd volume button at thesame time for about 10 sec u will see dat it turns on but dot let go keep holding it until the littke greent android guy comes out then it will have a menu but u wannah click on the first obtion nd after ur tablet is gunnah restart nd it will turn on aftertry pluging in ur charger nd if it worked for u it isnt gunnah have the red 'x' nd it will charge normally
Hope this helps u guys goodluck c;