Acer appears to be dying

I bought this Acer a few weeks ago and repotted it into a slightly bigger pot.

I've been away for the weekend and the top half of it seems to be dying. Did find a slug on it but assume that's a coincidence.

The tree gets quite a bit of light but also some shade during the day.

I was advised by the nursery that the green ties could stay on and would break when shoots thick enough. Some of them look quite tight around the stems.

I think I also put some bonemeal in bottom of pot when repotting it, not sure if this may be an issue.

Any suggestions as don't want to lose the plant. It hasn't been over watered as been away and been very dry I think.

 

Looks like the healthy part is from a separate main shoot...

 

Might be just wilted, give it a drink and see if it recovers.

Bonemeal probably won't hurt but I don't think it's ideal for Acers as it contains calcium.

 

Yes strange how other part of plant ok though I thought. Have given it a good watering in anycase