I know this is an old post, but it is 1 that appears near the top of a google search for "corsa d spanner after flat battery" search.

My battery went flat so I got a set of jump cables and got a jump start, after that my spanner light came on, I drove up the motorway to charge it but the light stayed on, the next day when I started the car the light went off, so I think it just means the battery needs a good charge and will keep the light on a fair bit.