Spoilers for
So the Pandorica was a trap, which the Doctor wound up in because it was 'broadcasting' a warning, including spacetime coordinates, which Vincent heard, painting the coordinates into his painting, which ultimately found its way to the Doctor.
Why does the painting show the TARDIS exploding, then? This doesn't seem to be related to the Pandorica. What do those spacetime coordinates have to do with the TARDIS exploding?
Of course, it might just be that Vincent 'sees more' than what's being broadcast.
.