Now when trying to put it into first gear the bike just cuts out.

Clutch is held in and when selecting first there is a clunk, the rear wheel moves a bit then the engine dies.
Initally i thought it could be to do with the alarm removal that i did - checked all the wires i disconnected - resolidered and still happening.
Then checked the sidestand, light comes on when its down and goes off when up, i assume this is ok as its all connected.
The bike was fine before and could engage and move in first.
Any ideas??
Thanks