2005 Prius Ate Key Fob, Not Starting or Turning Off -- Not Batteries... ?

I don't think this is either of the usual dead battery issues, as those are both only a few years old.

I sat in my car, on with the fob inserted, in the rain today for about 30 minutes when it flashed an error about "Unable to Engage Park Mode, or similar". I turned it off, and 30 minutes later tried to turn it back on, but it wouldn't start. All warning indicators turn on (see Photo 1) and the car makes a small noise but not normal ignition sounds

Then, worse, I cannot turn it off all the way! Sometimes all dash lights go off, but the Key Fob does not release, and the the small green light on the manual parking break button flashes without stopping.

Trying other methods, such as holding the Power button, with & without break, for long or short periods of time did not much help. Fob still stuck, cannot fully turn care on or off.

Sometimes the Shift position indicators would flash squares, around each [R] [P] [N] [D] letter (see Photo 2, edited to show squares more clearly) as it failed to turn on/off, and then those wouldn't go off at all until I kept pushing things!

Tried different things for ~5 minutes, waited 15 mins and researched suggestions online, then tried again and finally something got it to shut all the way off and release my Key Fob. Now planning on towing to the mechanic tomorrow unless I can figure out anything better to do.

Any idea what could be going wrong?

Photo 1:


Photo 2:

 

Thanks for the suggestions! It looks like the issue was my Key Fob battery dying while it was in the ignition!

The battery had been too low for remote functions for over a month, but I thought there was no issues with just inserting it for driving & using the manual key for opening/locking

Wellll it turns out that if the fob really REALLY drains, even while in the ignition, the car will start freaking out & doesn't want to release it!

But I popped in a new mini battery and everything is right as rain!