FWIW, this same sort of outage happened to them, albeit possibly on a smaller scale, in the early hours of 7th March (this year). I rolled up to the Cameron Rd McDonalds in Tauranga at approx 1.35am and they said their systems had just gone down, they couldn't take orders, and they were having to turn customers away. 

I'd be curious if current outage is down to "third party" incompetence, or deliberate cyberattack.