Email or call Home Depot... I rented a wet saw and it had a blade so dull it would break/chip the tiles at the ends of the cut. Had a spare blade from a saw that I previously owned, so I replaced their blade used mine and put the crap blade back on. Long story short, I contacted HD and they sent me a gift card for the amount of the rental plus $25.
They will probably try to charge you for everyday they are unable to rent the machine because they have no keys. Good Luck