DSO Quad won't start

Today I have received the oscilloscope DSO Quad. Everything seemed to be fine, it started once I installed the battery. Then I connected it with my PC and upgraded with new firmware. Then it started, I used it for a few minutes and it switched off. Now I can’t turn it on either with battery or connected to computer via USB. It doesn’t work at all. The polarity is fine and the battery has voltage of 3.95 volts.

Sorry for the issue, please send it back for replacement, we will do failure analysis and feedback to you.