What am I doing wrong?

[Fast Eddie]

Got a hong nor scrt10 and my new lipo arrived so I charged it up and then the wheels fell off (almost literally)

The electrics were an lrp quantum comp speedo, a 10t brushed reedy, a retro futaba receiver and I was using cells and all was fine.

I have bought a castle creations mamba max pro, an ezrun 5.5 and a 5000 50c lipo. The lipo arrived first so being impatient in it went.

The car flew around at tremendous speeds then stopped and the speedo felt hot. I changed the speedo to a ko propo but then I had steering and no drive. I changed the motor and then looked good to go.

Back outside the car went up and down the street then got a mind of its own. The last I saw it hurtled at frightening speeds out of view and came to rest with a huge thud into a local neighbours garage door.

Im now scared of my lipo, why did this all happen?