I have a 2006 Lexus IS 250....
I can turn the engine off, but for some reason, the radio, navigation, and display screen STAYS ON! When this happens, I can't even lock the doors and it beeps like it does when I get out of the car with the keys while leaving the engine running. Since the key buttons didn't work (lock, unlock, or pop the trunk), I assumed a dead battery immediately replaced it only to find out that that wasn't the issue... the car still did the same thing. Unfortunately, I had to leave my car in this state all night and manually had to "key lock" the door just to keep the car safe overnight. In the morning, it was STILL in that state but the engine cranked up as usual... after a very slight hesitation.
Also, the small display screen says "KEY NOT DETECTED" even though I just replaced the battery and can successfully start the engine.... and I tried the 5 second key to the start button to see if that made a difference... it didn't.
Has anyone experienced this? Any suggestions??