Hi mate, how old is the car?
mines a 2006 and the hood has done that occasionally recently...seems to be that the big boot panel is the heaviest, so its that that stops lifting first when the hydraulics feck up.
I also get the yellow hood symbol flashing (which you posted somewhere else)
Needs dealer attention to check the hydraulics. On mine I also ensure i raise/lower the roof with the engine running...gives more current to the mech giving it a better chance of working ok!!
If it stops halfway, raise/lower the roof via the normal button way, and if that doesnt work, manually lift the boot panel and pull the roof. works a treat, but obviously makes you look a plonker in public ! :-)