Bittle battery problems

i got a bittle from a friend who could not get it to work and gave up on it. after some troubleshooting i figured out that the battery was not supplying power to the NyBoard.

next i measured the voltage on the connector before and after pressing the button which turns the led on

both measurements gave 0V

after this i opened up the battery case and measured across the battery B+ and B- terminals.

this measurement gave me 7.8V

some observations on the PCB:

there was a layer of what i presume is flux on all the components

resistor R12 which i presume pulls down the switch Q2 was only 15 ohm

there was no connection between the ground of the battery and the connector going out even when the LED was on the LED turns off after about 15 seconds

do you have any idea where the problem lies?

.