Vacuum cleaner switches off immediately

I have this vacuum cleaner for only 3 months. It stopped working - when I press the switch button, the 3 LED flashing, motor is running for half a second and the device is switching off.

The device has 1 switch button: first press - half speed, second press - maximal speed. third press- switches off.

I checked the motor capacitor - it is ok. I connected the battery to the motor - it works continuously, thus the battery is not faulty.

The voltage that comes to the motor after pressing the switch button once is about 2v (even for lower speed looks too low). The motor designated voltage is 7.4v.

Any help will be highly appreciated.