Vauxhall Combo alarm dead help

hi i have just brought a vauxhall combo 1700 mkii dti, the problem i have is there is no alarm working at all. spoken to previous owner and he said he took of the battery and left it standing for a week, put the battery back on and now there is no alarm at all, i have done the key in drivers door and turned to front of van, but still dead no red blinking light on hazard ether. the fob i have has no working parts inside but have ordered another one to sync when arrives, will this activate the alarm back to life, the central locking works on the key in door, any help much appreciated as don't want to put my tools in and lose the lot..