2000 mustang, remote start

my buddy tried to install a remote start on my mustang and now it seems as if the factory alarm won't turn off and i can't start my car. the theft light on the dash keeps blinking and when i try to start my car i don't even hear a click from the starter. i need my car so can somebody please help me. here's where we stand. tried to install the alarm got it to crank, but not completely start played around with the wiring engine stopped cranking noticed theft light constantly blinking completely took the alarm out still not cranking HELP!!!!

sounds like transponder trouble to me. Ask him how he interfaced the transponder. If he used a module, it may be improperly installed or defective. If he used a key, it may be misinstalled as well. The theft light with flash like that if the car isn't seeing an RFID signal from the key or if it is seeing two different RFIDs. THat is where my troubleshooting would start. Check fuses too.Northstart.....or start it your damn self.

i checked fuses, he didn't install a bypass module. we didn't know my car needed one. i only have one key, is it possible for a key to become unprogrammed?

Usually on Fords you would at least hear the vehicle try to crank over.  If I were you, meter the starter wire which is WHITE/ pink and see if it gives you a 12v read when you crank the vehicle.  Also make sure that the starter wire isnt cut.

the starter has voltage, but won't crank. someone please help soon

Did your buddy cut the starter to wire up a starter disable? If so did you test both sides of the relay, or better yet take the relay out and reconnect the starter wire? There is the outside chance that your starter is bad. Try giving it a whack with a hammer and see if it starts. (no I am not trying to be funny)

Also, could you elaborate on "played around with the wiring"?

If you tried to remote start the car without the correct rf code the theft system will lock up. Put the key in the ignition and turn it to the on position and walk away come back in about 10 min and see if the theft light goes out. If it does start the car and go. If it don't start checking for unplugged harnesses under the dash near and to the left of the steering column.