Accidents happen. These are heavy objects getting transported around by people who don't care about them like we do. And sometimes they get bumped or dropped along the way and break.
And none of that is your problem. Contact your distributor and work with them. They will need to replace that lower cabinet at the very least. If they don't, contact Stern directly and let them know your distributor sent you a machine with a broken cabinet, and they are not working to replace it. Work with them at first, and give them a chance to make it right. They won't replace the whole game, but they need to replace the cabinet. If they don't, scream a bit louder, and then scream very loud.
Flat out, that is beyond the line of being acceptable. Is it a fairly easy repair? Sure, but it would always look like a repair. And if you don't do that type of repair normally, it will end up looking like ass. So have them fix this one. And if they send you an unpopulated cabinet, have them also send someone to do the transfer (unless you know what you are doing). Just give them the chance to make it right before going off the deep end.