I had similar issues with an Astra Turbo i had, i would try to start it in the mornings and it wouldn't go, so left it on charge all day and then it started, left it for a few hours and again nothing, not even a click !

Tried new batteries and alternator and then discovered it was the electric aerial causing the problems.

Try taking the positive off the battery when fully charged and then just touch the terminal on the battery to see if that gives you any signs, my aerial started clicking and then i knew that was the fault..