Vantablack 310 only reflects 2% of light across the entire visible and near-infrared spectrum. It’s only a minimal diminishment in performance because the original coating reflected less than 0.1% of light.
(obligs)
so black, it goes to 11!
Vantablack is lauded for its light absorption capabilities. However anything that absorbs must also re-emit (except for perfect black-bodies). Hopefully vantablack re-emits in a wavelength that the atmosphere is opaque to, such as the 5 micron to 8 micron infrared range. Otherwise they’re just shifting thd problem to another band.
Perfect blackbodies still radiate – the meaning is that there are no wavelengths they tend to absorb or emit more, so it just depends on the temperature. For a black object at our distance from the sun the equilibrium temperature is 278 K, just a little cooler than us (we reflect more but also have a greenhouse effect). So all else equal – i.e. no battery adding heat – it would radiate about the same wavelengths that Earth does.
As soon as I put that text in parentheses I assumed a correction would be forthcoming 
“It’s the wild colour scheme that freaks me,” said Zaphod whose love affair with this ship had lasted almost three minutes into the flight, “Every time you try to operate on of these weird black controls that are labelled in black on a black background, a little black light lights up black to let you know you’ve done it.”
Just take a can up, put it in the module, seal the module off, and depressurize.
Space walk outside the module with a bucket of soapy water. Brush water over the outer surface and you’ll quickly find the leak because you’ll see bubbles. Easy peasy.