The shield drone. It must have been being used as a decoy. Finding 13B herself would prove far more difficult as she didn't even need to breath allowing her to sustain absolutely zero movement. Something seemed off about the shield drone's defensive bubble though. It must have had time to charge meaning it would likely sit there unaffected for another emp strike not on the scale of the grun. [spoiler]grun is pretty much a kaiju sized EMP robot and damn does it have a sad backstory.[/spoiler]