You have to fend for yourself when making one on one transactions through Craigslist, which has no seller rating tracking system like Ebay, it sounds really dumb that you didn't test the thing before handing over your money, buyer was not beware?
The worst thing that can happen is being sold a stolen item, perhaps with tracking software that allows the authorities to find it in your possession.
I am not sure that the police would even act on this, it may be more of a civil matter that would typically be handled in small claims court, which after fees everyone might be losers. Since they are not an established business, you probably can't get them for violating any advertising regulation clauses, if they were a retail store not delivering on their ads you could complain to FTC.gov, or maybe report them to the numerous scam registries on the internet.
Did the advertisement say that the tablet worked? If the ad says that the tablet worked print out a copy of the ad and file a police report. If not you're a fool for not testing it before handing over the cash. This is a dog eat dog world, try not to get bit. You could chalk it up to a lesson learned if all else fails.
"Fool me once shame on you, fool me twice shame on me"
The police are here to keep the peace, not protect you from making foolish decisions. If you paid less than $50 for the tablet it's considered a "petty crime" and they won't bother to help you at all regardless of what he said in the advertisement.
In the UK a private Sale/Purchase carries little protection for the buyer and it is very much a case of buyer beware. According the the Consumer Associations Legal department there are only 2 requirements ~ the seller must actually own the item and it must be as described. If the seller did not actually say it was in working order or wording to that effect such as good condition, then you have not got a leg to stand on. With computers be very wary of an add that merely gives the computers' specifications but makes no mention of its condition. With an add like that you have no legal come back if it is as dead as a dodo.
you need to report him to Craigslist first
and report the threat to the police so they can find him and you get your money back
safe
Drive to his house and request a refund, if he still refuses call the police.
I bought a tablet from a guy in town off of craigslist and when I get home the thing wont work and then when I try to txt him he wont answer. then my sister tells him that shes going to report him he threatens her, what do I do? I really need that money back and I've never had this done before