Yes, the police can arrest you, because the word of the store that you were trying to rip them off is all they need to give them probable cause.
All probable cause is, is just a reasonable belief that a crime may have been
committed and that a particular person may have had
something to do with it. Probable cause is a very low standard of proof, and basically almost anybody can get someone arrested if they really want to do it.
In order to get a conviction, on the other hand, the DA would have to prove that you intended to commit this theft
beyond a reasonable doubt. That's a much higher standard of proof. And if the DA cant meet that, a jury would have to acquit you of these charges. But whether it's an easy case for them to win or a hard one is irrelevant -- the DA is entitled to prosecute you if they think they can make out their case.
That this could have been a factory defect or that someone else might have returned this as defective before you did would be facts that could help you with a defense if you want to fight these charges. But disputes as to facts are what criminal
cases are all about. So it won't get the case dismissed. Questions of fact get resolved by a jury if you want to take the case that far.