Prius (2004-09) :: Stuck In Endless Locking / Unlocking Door Loop Drained Battery

I got the car running again, so no need to go into details on that (I used the physical key on the keyfob, you really do have to turn it further than you'd think, but that got me into the car, after several tries was able to get it to stop cycling through the locking/unlocking and was able to jump it).

Got the 12v battery in my Prius replaced by the dealership in the last 2 years. Last winter, one day my Prius refused to start even though it had been running fine earlier that day and was parked in a semi-heated garage. Jumped it and got it working.

Last Friday I went to get out of my car and my Prius kept beeping at my any time I had the door open, and the clock on the dash seemed to be a little dim. I doubled checked that the keyfob was in my pocket (and not in the holder thingy), eventually the car seemed to lock fine and I went up to my apartment. Didn't drive the car until this morning.

This morning I come down to find that keyless entry does not work, nor does pressing the unlock button on the keyfob. (The car is parked in heated underground parking fyi.) About every 1 second on repeat, the car is making this sound like it makes when you hit the lock/unlock button from the inside of the car, so it seemed like it was stuck in an endless loop of locking or unlocking. I go back upstairs, leave my key fob in my apartment (which is around 300 meters away or so), come back down - it's still on the loop making that sound.

I get into the car with the physical door key, try starting it - the lights will come on but the car doesn't seem to actually start. And the endless lock/unlock loop starts up against once I turn the car "off". I got upstairs and switch to my other backup keyfob. Come back down. Car is still in the endless loop. Try to start it again, car still doesn't seem to start, but this time when I turn it "off" the endless lock/unlock cycle finally stops. Do finally get it running by jumping the battery, then it seems to run fine.

So I bring it to the dealer, and the guy their rather vehemently insist there must be something wrong with my keyfob. First he immediately confidently assures me that I just need to replace the battery in the keyfob, which makes no sense. Then he changes to saying he thinks the lock button on the keyfob was stuck down, which doesn't make sense either as like I said it continued doing it even when I removed any keyfob from being anywhere near the car.