Momo’s arm supporting Denki as they walked to where majority of their classmates were, either unconscious or injured. A helicopter nearby to carry whoever they can to the hospital. Momo’s phone nearly dead and destroyed was displaying a video from the news for Denki, to catch him up on what he hadn’t seen.
It didn’t take long for him to start crying watching everything that happened, everything he could’ve helped with, but didn’t. He saw his classmates, his friends, teachers, heroes, everyone he cared about get injured and killed (though, Katsuki was okay somehow). He saw how they all kept fighting until they couldn’t. It was too much for him to handle.
Momo sat him down by a few unconscious classmates, near the helicopter, then gave him her phone so he could continue watching all the fights he wasn’t there for.
(Haven’t watched the new season yet so sorry if it’s inaccurate)