When both LEDs are on then Tango either locked itself due to PC USB port malfunction or was physically damaged and/or tampered with.
You can do the following:
Connect Tango to a working PC and let it stay On for several hours [24-48h]
This will help if it got self locked due to PC USB port malfunction.
If this doesn't help then the programmer was physically damaged and has to be sent for inspection and repair through the distributor it was acquired from.