Last week I took my 2004 into the dealer to have the computer recall work done and everything seemed fine for the first couple of days. Yesterday I got out of the car and left my wife in the passenger seat talking on the Bluetooth as she had her own fob. I left it in park in the on position and she just hit the power button to turn it off. Later, when I got in to start it up it wouldn't go into the ready mode and I got the Master Warning Light display (triangle with exclamation point). I tried all the tricks I could remember from Prius Chat postings and none of them worked. I couldn't get the screen to come on and the windshield instrument panel showed the above warning light and occasionally the squares around the gear shift displays came on and blinked when I tried turning the car on and off. Occasionally the air bag warning light came on but I couldn't get it to go into ready no matter what I tried. I even got out of the car and locked it, then it wouldn't immediately unlock with the smart entry feature!! Eventually I gave up and called the Toyota roadside service people and they were going to have it towed for me. I then got back in and the car started! Go figure! It's been fine since! You can guess that I'm kind of nervous about it. I have 30k on the car, I've owned it for 15 months, and have had zero problems previously. Is this operator error or somehow related to the recall? Any ideas? How do you re-boot? I thought I had all the idiosyncracies figured out and still REALLY like my Prius, though I'm not a technogeek.......
"This sort of thing has cropped up before, and it has always been due to human error." Stabbing at power button bad. The simplest explanation is that your passenger hit it twice, putting it into IG-ON (since of course her foot was not on the brake at the time), and then you walked away with the fob... into COMPUTER HELL!!!!
I'm suspicious of operator error. I think perhaps the 12v battery got drained pretty low (The car was in IG ON, not READY--is that correct?). For whatever reason, when you got out and left the vehicle completely shut off for a bit probably just enough charge remained in the 12V to fire up the computers to open the circuits on the HV battery which immediately recharged the 12v and all is well. Weird things can/do happen when the SKS fob is kept in the car when not in READY for prolonged periods. The system quits sensing for the SKS. But usually, in that case, once you get out, lock the car, then get back in that turns everything back on. So, in your case, I don't think that was the problem. Like I said, my money is on the 12v. For peace of mind have them check for a DTC code (either at the dealer or AutoZone) if you like, but I doubt there's any serious problem. EDIT: Reread your original post...I stick by my 'drained 12v theory'--but suspect that your wife may have hit the Power button twice and put it in ACC mode instead of totally powering down.