You definately need to install the other motor when you switch to lipo. You can cook your 4 in 1 or your motor with that 11V lipo. Don't fly again until you change the motor. And install the heat sinks. Use some heat sink compound if you have some.

I don't kinow what happened to your brother's CP. Does the light on the 4 in 1 go green? Make sure your throttle trim and throttle are down before you plug in the battery. It won't initialize otherwize.