Smithkjnc

Hello.
Just purchased a 2004 six speed RX8, 140000 on the clock and seems to run very good. However, I parked it the other day and the next morning I went to start it and it would not turn over.
Brand new battery, all dash lights come on and everything seems to work except the starter.
I then noticed the car symbol with the key blinking rapidly. After a minute, it started giving a code 1-3
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I have searched and found various articles on the flashing red key that keeps the car from starting.

The thing is that I only got one key with the car.. And it was not the original. So I don't want to take it to the dealer... We all know how they like to bend people over.... But what I did find is another 2004 in a local junk yard exactly like mine. Can I just take the Ecu and key from that one and replace it in mine to take care of the problem?