allo mate ive had a lot of experience with toad alarms and its sounds like u have a very poor b+ feed blown fuse or a bad earth i take it is on ya fiesta xr2i . u can drop the fuse box down with 2 screws , there will be 2 black wires running into there with 2 inline fuses check them first as it is possible the alarm fitter has wired the window close to this feed instead of a separate 1 ,which has possible blown the fuse, if it snot that remove ya kick panel and u will proly find to black earths that run to the car body give them a clean,