Boyfriend accused of breaking something at work with no proof, being forced to pay for a replacement

Basically, a radio from his work was damaged by some mud or something, they THINK he was the last person to have it, he swears up and down that he hadn't seen it in over a week. Without any proof, they're taking 200 dollars from his paycheck to pay for a new one. From what I've seen online, while they are legally able to make you pay for new equipment if you broke it, they can't do so if you make minimum wage, which he basically does. How would we go about fighting against this? This seems so unfair and he wants to just fork over the money so they'll stop harassing him about it, but I think he should fight it.