Wouldn't start

[YesIneedAWD]

I have a 2018 XC90 AWD T6. I had a weird situation today and wondered if it has happened to anyone else. I went to start my car as I normally do. (Press brake, turn switch on) The brake would not depress, and the car would not come on. Radio and air did. In fact, air blasted but said it was off. I called the dealer's service department, they said to call roadside assistance. When they came out, the serviceman turned the car right on. No problem. I drove it to the dealer, they called back to say that the couldn't see what I had described, but the software did need an update. I would rather hear it was fixed by update. They also said if the vacuum was off, the brake wouldn't go down. (I don't even know what that means.) Anyone?
I should say I have had no other issues--car drives like a dream. I had the first version when it came out in 2002ish--that was so trucky.