Hydraulic fluid issue after tyre change

[TomReyno]

So I took my motor in for a tyre change, both front. I drove away only to have the car beeping at me and the red exclamation mark on the dash. I pressed one of the black thing's down on the dash and it said "check brake fluid, check hydraulic fluid" - plenty of both....so I am lost lol.

Any idea what this could be or what has caused it? 

Cheers for any help!

 

[Audi Owners Club.]

Was it only the tyres that the garage replaced?