alarm has killed the car!

[luke.w]

Has anyone had an alarm go bad on them before. Mines a Foxguard and I could not switch it off at all. Two functioning key fobs made no difference - had to disconnect the battery and let the alarm back up run down! Now the entire electrical system is completely dead! Nothing at all despite re-charging battery, not the slightest flicker of any electrical activity. Checked fuse box and nothing apparent there either. Is there a main fuse anywhere? All other fuses look ok. Has anyone ever encountered this before? Any suggestions? Thanks.