So I'm sure this is a retarded question but here I go,

I have 2 plastic water 55 gal storage barrels, well I sealed them up when it was hot AF outside and the temperature dropped tonight causing them to very partial "collapse" (sides dented inward) much like that well known demonstration.


Can I reverse it by trapping cold air inside of it, and when it heats up tomorrow in the sun?

The lid was fairly hard to get off, good amount of air rushed in when I opened them, No liquids or anything inside they are empty.