Saw Blows Fuse?

Seasons Greetings,
Hi,
I bought just before Christmas on Ebay a Black & Decker sliding compound mitre saw. Described by seller as brand new, unused unwanted present. I've just got around to checking it. The laser light comes on but when I switch the saw on, nothing happens and the plug fuse blows. When I lifted the saw head up with the laser light on. The saw switches on for about a second then cuts out blowing the fuse.
I've tried several times no luck.
Any help appreciated.
Cheers.