How do I restart my vehicle after security system shut it down. on 2013 GMC Yukon Denali

Will not start after my husband unplugged the radio components to hook up something to my radio. Only makes a clicking noise and security lock is flashing or illuminated.

Asked by for the 2013 GMC Yukon Denali
sounds like he accidently tampered with the anti theft system and removed something he shouldn't have. It won't start until this component is put back in. radios are stolen quit often and as a security feature this is the result