Lexus is300 security light problem

I have had a problem with my Lexus i300 where the
car doesn’t want to read my key and therefor I am
not able to bypass security and start my car.
Everyone and then I would be able to put my key in
and the light goes away but it got to a point where I
wasn’t able to start it anymore so I got a new ECU
for the car that came with a programmed key
because I thought that was the issue but now it’s
still not reading the key and the security light keeps
blinking.

any suggestions on something I should do or look
at??