security/electrical problem

What is your question?

i have a 96 xj6 when you lock or unlock the door it do not beep no more it use to beep but not not more and now the security light came on when i drive the car the security light stays on.i checked all the fuse and battery everything is good.sometimes it wouldn't start.maybe after 3 to 4 hrs it start sometimes it take days to start.does anybody no what the problem is.how do i fix it.how do i reset the alarm system.and what happen if you have an after market radio.