Your problem seems similar to mine just that you have only the drivers door opening.
Mine will open the 2 front doors but not the back doors.
I was in with Denis Mahoney off the M50,they are Toyota/Lexus dealers and I asked about the back doors not opening.
They said "No never heard of a setting to change that".
They wanted 100 euro an hour labour for me to leave it in to them so they could look into it.
If they had said "Yes its a setting" id have paid the 100euro but I wasn't leaving it in for them to go on a fishing expedition at my expense and then charge me 3 hour labour for a 5 min job.
They don't have the Lexus franchise very long so might be worth ringing another Lexus dealers and see what they say.
Have you tried resetting the lock setting on the key fob.
Its in the owners manual.
You stand outside the car, press and hold the open door button on the key fob.(im sure its the open door button cause when I kept the closed button pressed all the windows went down)
Car will beep and indicators flash.
A picture on dash will come up of car with only the drivers door open.
Press it again, keeping it pressed and you should see the picture come up with all 4 doors open.
Try the doors and see if its worked.
I have done this but still only my 2 front doors open, not the back 2.
Its in the owners manual as well.
Let us know how ya get on.
gussie