imo
trying to open a dumpster to put it into. unable to get the lid up (locked?) so he gives up and leaves. maybe looking for another dumpster.
ohhh great thinking.
IF this is the same guy, this is happening before he'd get to nancy's house, we believe, right? maybe trying to find a place to stash it with plans to return to it after taking her so he wouldn't have to bring two big backpacks?
just speculating, IMO, etc.