Magic Mouse continually flashing light

We have had our Imac and magic mouse for a fortnight and we are experiencing problems with the Magic mouse!! It dropped on the floor earlier and the batteries fell out...since putting them back the light on the back is continually flashing and it does not appear to be making any connection to the Mac. We have tried changing batteries in case, have gone through system preferences etc on the menu and nothing appears to be working.

Any words of advice would be greatly appreciated.