hsahota

Hi Members, This is my first post and apologise in advance for any mistake I make, I had a search in the posts, much valuable information, but couldn't find answer to my problem,
I recently bought a Lexus GS450H 2007 in UK. It has done under 30,000 miles and was in good running condition until recently.
Unfortunately I was away for few weeks and on my return it did not start. Both remotes would not operate the central locking. Replaced batteries for both remotes. still not operational.
12v Battery low, jump started no luck. Removed and recharged Battery out of the car from 8.v to 13v. Drained battery with 250A load for 20 sec. and battery still maintained its voltage to 12.9v. Battery date 200520. so it seems to be okay.
Next connect the 12v battery, new batteries for remote. Central locking still not working.
Now opened the door with key. security red led flashing between 1.5 and 2 sec.
Then when I move out of the car and shut the door, It shows on the display "KEY NOT DETECTED". and when I open the door with the key and go in the message disappears.
I am able to open and close the windows, hoot and operate the lights . The brake lights come on when the paddle is pressed, but the ready light on the power switch does not come on.
I also tried by putting the Remote next to and press the Power Switch and the Brake Paddle, it does not want to bring the Ready light on and start. Tried with both Keys.
The 3 fuse on the Positive lead are ok.
It would seem like its lost some communication/ programming when the battery got drained.
Is there something I have missed.?
Thanking you in anticipation.