Help with lrp sphere / x11 5.5

[Davidagriffinuk]

Help,

i tested my b44 outside with an lrp sphere 07 competition + fan cooling set, it ran fine, didnt get hot but then stopped i just assumed batteries run out. Another set of batteries a day later and it revs up fine whilst holding it but put it on the floor it goes 5m then stops suddenly with steering servo still working. The yellow light flashes on the speedo cant remember if any others were maybe blue? It hasn't got hot cos it hasnt gone anywhere.

The controller and motor are both brand new. vector x-11 5.5

Any ideas, experience required as this brushless stuff is new to me