how to kill scarab crab halo 3?

[Andrew]

i can get in the thing but dont know what to do i see a big blue screen witch doesent get destroyd and some green lights please hep ps the man keep saying destroy power source or somthing

 

[hash master]

you have to get on it then walk around until you find a red orb thing on a wall shoot it until it blows up and then when you hear sirens get off and run away then it explodes

 

[tripred97]

go up to second floor go to the side and walk on the edge untill you come to the middle destroy that with mines