I bought my son a flysky gt3b and waited for ages for it to come from the supplier only to find that it was faulty.
Eventually the supplier refunded my money as they wanted me to send it back (which would have cost more than buying as new unit).
After being refunded in full we had nothing to loose, so we took it apart. We put the battery's in and noticed that it was turning off and on as we wiggled the battery box cable.
We traced the cable down to the PCB and found that the connector had not been pushed fully into the socket. After making sure it was fully home, we tried the on of switch and it worked from then on....
Since then we've converted ours to lipos buying a custom made cable and it is still working now!
I know that it is a different model, but it is worth a shout.
Regards,
T_2