As you note, it’s pretty heavy. Must have been really hard to carry inside to begin with.
Handtruck, maybe? the more important question is, why? If there's ice in the rain barrel, who cares? If it's cold enough to freeze up, it's cold enough that you're not gonna be watering your plants or washing your car anyway.
And if, for whatever reason I can't fathom, you need to melt the ice in your rain barrel, wouldn't it be easier to tote a kettle outside than to tote the barrel inside?