Immo locked happens for many reasons, when bcm,ecm,immo ring has been replaced, wrong code entered  and also when the vehicles battery goes low. many vehicles will not get out of immo locked unless a reset is done after the programming of the immobilizer keys or fobs or  if this modules were replaced or what ever other reason caused it . in order to get it out of locked mode one must insert key and turn ign  on for 5 seconds then turn off and remove key for 5 seconds and must be done 3 times. battery must not be low on charge. never heard of formatting an antenna.