I've recently installed a wiring harness from behind the dash and rear of the car its an oem harness out of the same year as mine.everything powers on and all the electric seems to work i.e lights, windows, locks, windshield wipers ,etc.
but when I turn the key I get a red blinking car with a key beeping and the car won't start please help.

 

Key is likely not registered anymore... Likely will need to be programmed

Either that or you have a fault with the key coil or part of the system that recognizes the key