Hey. Sorry, just saw this.
My .02... I'm not a professional board repairer but I've repaired my share of boards in the past. I'm sure there are people near you and on this board who may have better advice, but from my experience...
It's really hard to tell from that picture if there's some real damage underneath either resulting from or causing the blemish, but from what I can tell from the picture it looks like it could be just a cosmetic scratch. The paint blistering could be caused by a million things, including the scratch in the paint. If it is just the paint, I wouldn't do anything to it.
If you fear that there's water getting into the board (you can usually tell by sucking on the area... If you're able to suck water out of it then the issue is bigger, though if it's been sitting out for a while this may not work) you should sand it down to see see what's going on underneath. Make sure you sand like an inch around anywhere that the paint has come off if you do this. It appears that the crack may extend to the pad. If that is the case you're gonna have to peel back at least a little of the pad so you can sand around all areas of cracking. This will also allow you to see if the crack extends further into the board than you could see with the pad on.
If there is damage to the board under the paint you'll have to repair it. If it's really minor, a ding from banging into something (and not a more significant stress crack from a large or repeated impact or something of that sort), just sanding down and solarezing should be fine.
If, however, the damage is the early stage of the board buckling, you'll want to sand an extensive area (like 5" wide wrapping from the bottom to around 6" in on the top), wrap it in glass (two layers of 4oz cloth works for me, each layer should be several inches wide, think I usually do a 2-3" wide layer followed by a 3-4" wide on top, extending from the bottom, around the rail, and like 5" at least towards the center of the board on the top. Our surfboards are EPS, so make sure the glass and resin is compatible. A little resin against the board, apply the smaller cloth, impregnate it with resin, apply the 2nd layer of cloth, resin again, smooth it down, sand when dry. Paint if you want, glue the pad back down and you're good to go. If you really fear that it's started cracking from repeated impact across a significant portion of the board you can do the same to the other side as a preventative measure.
If you are in doubt about how bad the situation is or you're not sure what to do, take the board to any board repair shop, tell them it's EPS core, and let them fix it for you. No matter how many repairs I've done my shit never looked nearly as good as a professional repair, and they're usually pretty reasonably priced.
Good luck and if you have any other questions feel free to hit me up (wherever you got the gear from).
-Dan