Never used it before, but this last week, we had vicious horrible heat and hot blasting wind, the kind of hot wind where you can watch your plants shrivel and die as tho’ someone was using a torch on them. So, since I had just gotten $135 worth of new plants after a javelina attack, I watched my new plants die and said OK, I’m trying this 1 year warranty. So easy! They scan your receipt, scan the pots with the dead plants in them, and bam, I got my $$ back. I know HD muscles their vendors hard for what they want, and I hate that here in AZ HD offers totally the wrong plants for the seasons here, but damn!
Home Depot is awesome; they’re super helpful and quick - no bullshit.
Oh and also their theme song that plays in their commercials is fucking awesome.
Does Home Depot require that you bring the dead plants back to show them? Would photos be enough?
A hallmark of sleazy online plant sellers is a requirement to ship dead plants back to them at your expense in order to get a refund or credit.* It wouldn’t be as annoying to return them to Home Depot if you don’t live far away, but still…
*even then you may be SOL if you didn’t save the shipping label from the original package.
The only time I would ever use a plant warranty is if I received a clearly diseased or damaged plant. Anything else is on the gardener, and not the fault of the grower/seller. Weather happens, marauding children, pets and wildlife happen, and pests happen. None of those things have anything to do with the health of the plant when you planted it. 
I save the original pots & just stick the carcass in it!! Pretty sure you need the dead body.