99 gt wont start... theft protection maybe..pats... help please!!!!!

[auggydoggy502]

just got a 99 gt convertable. car was not taken care of at all. had a junky alarm on it. wouldnt start half the time so i took the alarm off thinking it wasnt bypassing the factory anti theft. worked perfect for a few days now it wont start, nothing in the car works except the radio and the power door locks. anytime i go to use the power windows or adjust the power seat it sounds like a relay is flickering back and fourth under the dash and the seatbelt light on the dash is flickering on and of to. its the box to the left of the fuse box that the noise is comming from im pretty sure. not sure if this is the ecm or what. please help. had to have the freakin thing towed after stopping at the gas station and it wouldnt start up. thanks!!!!