At this stage, it sounds like there's some life left in it - to be honest, if its been planted less than a couple of months, I'd lift it out of the soil and plant it in a pot with some good potting soil, water it thoroughly and keep it watered as necessary. It's obviously suffered serious drought, and shouldn't really have been planted at all during the very hot weather - keep it in a pot till autumn, then replant, keep watered until late October (unless you're up north, then you can probably stop beginning of October, but it depends on the weather).
When you lift it out of the ground, if the rootball is bone dry, soak it in a bucket before potting up. The point of telling you to put it in a pot is this - it's much, much harder to keep a newly planted shrub sufficiently well watered in the ground than in a pot - water needs to penetrate six inches deep to make sure the whole of the rootball has had sufficient water, and that's a tall order in a hot summer.