could be cable stretch. behind the lever in the cabin, can you see the cabin end of the cable?
if so pince it with long nosed vice grips and pull it further, it may just open the hood.
otherwise, Are you sure that it is not releasing?
get someone to lift the hood lightly while you operate the catch just to see.
On my Kia which is a similar age the release cable is quite accessable when the hood is open, take a look at another i10 and see where the cable is placed.
worse case, you may be able to cut thru it, open the hood and replace the cable. At first glace the cable in the ceed appeared to be DIY replaceable.