Put it on the car, to try it, and you've effectively accepted it as being OK so you run the risk. Return it now and it's absolutely not you that's damaged it by fitting or using the car so must be damaged by the courier or sent from the supplier like that. Therefore giving stronger grounds for replacement.
From the date you posted on here - guess you ordered (purchased) before the first of this month - if it was on or after the first the consumer rights changed in your favour to have a prefect product supplied or replaced.
Personally, If I got that - it would be going back - I presume you paid a fair price for it (not silly/suspiciously cheap) so you should expect a decent product, 'fit for purpose'. Think of how you feel if the next person orders from that company pays the same as you but gets a perfect one - and doesn't have the worry you have now of will it be OK or not - is that fair or right?
Hope it's sorted soon....