This story is a warning to all prospective buyers of second hand Apple laptops... I own a mid-2015 MacBook Pro and use it for high-end photo and video editing. It’s got a great spec but was lacking the space/ram and power to grade 4K footage, so I decided upon an upgrade. I aimed high - for the i9, 32GB ram, 1TB HDD Mid-2018 MBP. To buy new I’d be looking at around £3500-£4K, and second hand, around £2800. For this, as with many gadgets I go for Gumtree (risky but occasionally rewarding). Of course I spotted plenty of scams and I looked out for any that looked like a genuinely good deal. A while later I came across an ad that seemed almost too good to be true - the specs were what I needed - at almost half the price of a brand new machine: £2000 - and it looked almost new. What made it seem all the more genuine was the fact that I could meet the seller in person, see the Mac and decide for myself... I managed to get to see it first and even secured a further discount. Feeling pretty happy with myself I met the guy, who told me he was also a graphic designer who had been given a work computer and no longer needed his Mac. He seemed pretty gutted to sell it. Nothing seemed out of the ordinary, the Mac looked legit - he changed the login password for me and I paid cash. When I got home I set about starting fresh. He’d done a clean install but out of respect for his privacy I didn’t want any of his files remaining. So I put it straight into recovery mode. That’s when things went dark. Firmware lock. Until this happened to me, I had no idea about this type of lock outside of iPhones and iPads. I've purchased a number of second hand Macs in my past and never had an issue. Had I known about the firmware lock, I could have requested putting it into recovery mode and either retrieved the password from a legitimate seller -or- watched them panic. I tried calling the seller immediately, his number was dead (sim probably tossed in a bin). Tip 1 - ask to reboot in recovery mode. Upon Googling about the FW password it became apparent that this was very bad news. Of course Apple won’t reset it without a receipt. What this meant was that I could never fully wipe the computer, use recovery mode or use target disk mode. Annoying... but not the end of the world maybe? I noted down the serial number and called Apple for advice. They didn't offer much insight other than checking if the machine was stolen. At that point I noticed that the serial number in the system profiler didn’t match the serial number on the bottom of the machine. Again, Apple couldn't figure out why, but put this down to the idea that perhaps the seller had scratched or dented the original and bought a spare part to give it that shiny new look - again - not the end of the world, but very suspicious... Tip number 2 - check the serial numbers match. Then it dawned on me - if this machine is in fact stolen, then upon connecting to the internet, it could be remotely locked and would become a very expensive paper weight. I checked the serial number on a few online databases for stolen devices and it came up clean. At least I would have no luck contacting the owner through the police. I was determined not to become the second person to lose out from this machine. But what if the guy who sold it to me was waiting for me to go online, lock it, then act like he’d had it stolen and take it back? They’d even get a location of my house and maybe break in and take it? I hadn't connected to the internet yet and I didn't plan to. Suddenly I had a powerful i9 machine that had no internet connection. Not a good thing at all, especially in my industry... it's pretty much useless. I didn’t tell my wife that I’d lost almost £2K and hid it, hoping to think of something soon. I didn’t get any sleep for a few nights and was fuming at the idea of being scammed. I came up with a list of options: ask Apple if they could take it as part of their recycle scheme and get a discount on a new mac (not likely), sell it for parts, use it side-by-side with my Macbook Pro and keep it offline. Every option sucked. Especially as Adobe need me to be online in order to validate my account. Every now and again I'd take it out from hiding and look at it. I noticed a few more things that were strange. From the finder preferences, I could only show the Mac Hard Drive icon on the desktop when I had ‘Show CDs, DVDs and iPods’ ticked... Also the 1TB hard drive in system profiler was only showing up as 250gb in Finder. Tip 3 - check disk space in Finder matches what you're being sold. I took the Mac to a friend who could poke around a bit more. He managed to reset some things in Finder and sent me a screen grab of the About This Mac. I could see the system profile serial number now matched the one on the bottom of the machine... A lot of the details had also changed: 16gb ram instead of 32, i7 instead of i9... I had been scammed alright. I’d purchased a 2016 laptop disguised as a 2018 machine. The system info had been carefully manipulated and then the computer was FW locked (in hope I’d never find out)?... With a simple Google search it's easy to find out how to manipulate the system info. This should be permanently locked - please take note Apple. I feel annoyed that I was duped and it cost me sleepless nights and heartache, but I should only be annoyed at myself. If I’d followed even one of the three tips above, I would have been suspicious enough to walk away. I hope this post will warn anyone out there who could make the same mistake as I did. It’s very easily done and a real pain in the ass.