This is my first post on a surfing forum so go easy!

My mate moved away and left me his board - a 6 foot 3 fibreglass thing with foam in the middle. It's in pretty bad shape, but I'm experienced in fibreglass repair so no big deal.
However, he has seemingly poured glue all over it and covered the glue in sand, so now there's like a layer of sandpaper all over the deck. Should I sand off this layer of sand and restore the board to a shiny surface ready for waxing?
Cheers!
Alex.