Immobilizer light flashing?

So, I had recently lost my keys which had the original key on it and was the only key I had for the car. I had to have a locksmith come out and make me a new key. After paying for that I had ordered a key fob I believe its called its the remote that you can use to lock and unlock the car remotely and can trigger alarm. I tried to program the device to my car by looking up the procedure online and it told me to turn the ignition on 3 times then to open the door 3 times then press the unlock button. When I tried to use the buttons on device which it didn't work. I was in a hurry at the time so after it failed to work I had left. When I came back that's when I noticed key was not working and the dash immobilizer light was flashing and the key wont start my car. I cant get it out of the immobilizer mode how do I? What should I do now? I disconnected battery for over 15 minutes and then for a few hours but that didn't seem to reset program. Is there any way I can bypass this issue? Or reprogram the key?