After going to HMV, John Lewis, Sainsbury's and two Games, I finally managed to find a Arcade manufactured in March 2009, in the last Game. The other one only came up with a 2007 model (so non-Jasper), HMV only had September/October 2009 and John Lewis only had one which was quite recent as well. Sainsbury's (well my local superstore) don't even stock 360s.
It's Lot 0915 Team ABIR and the Dash is 7363

I know that I musn't update the dash and I won't be going online with this box, but I was wondering if there's a "safe" game I can use to stress test it, just so I can check it's not a dud before I start pulling it apart and void the warranty.
They were poorly coded and will push the hardware really well. Perfect Dark Zero is a good example