cannot play video

[lightmtl]

After my tablet upgrade 5.1.1, it can not play video. It can only play the video I saved before update. I am Montreal canada. There is no repir center , so I can not get flash tool to downgrade.  Any one can help me ? 

[lightmtl · Accepted solution]

I just fix the video problem.

I format the sd card in my computer, replug in the sd card, as a new sd card. I transfrred the video that was not able to play before. now it played!!!

The reason I have to format in my computer is the data in sd card can not be eased even use format in tablet.