Flat battery when I tried to start the car after sorting those stupid vents. The battery has been slowly going down for some time so a replacement was on the cards.
Mine is a stop start so the battery works out and nearly double than the basic model, a cool £174 Varta 70aph followed by 1/2 hr to fit it myself and it was off the have the codes reset. But not the £89 and 1/2hr quoted by VW dealers but 10mins and a 20 note to a friend in the trade followed by a 120mile test run.
Re the vents, if you have a Golf or any of its derivatives you have a problem waiting to be sorted, don't think you will escape it because you wont, none of you will. As for the rust caused by the inescapable ingress of water into the seams, checkout the video online of a Mk7 stripped down to its bare shell, the rot is clear and obvious.
I suppose its what we should expect for a car made in latin America.
Another problem noted during the strip down of the rear bumper, the offside corner was 3/4" lower than the other. Quick check revealed the shocker had a small leak. So a pair of Bilstein B4s and springs on order.
Mine from new in Oct 2016 37k miles.