Tango 2 Problem

I have my Tango 2 since few months but only used it 5 times with no problem until Yesterday. After a little session, when I came back at home and tried to used it for simulator I discovered that my Tango 2 was not working any more ! I can’t turn it ON and no light when I used the cable to charge it.
I removed the back to see if the battery was unplug but everything seems fine inside. I need your help

I found the problem, the battery is at 3.09V … don’t know why, it was full yesterday