Can key fob loose connectivity? Intermittent failure to start

Some of you may have followed my other thread about my brother's truck (2023 SR5) not starting intermittently. The only thing consistent is that when it does not start the key icon light also does not come up on the dash. When the key icon comes on, the truck starts right up.

So it seems that randomly, after a multi day sit, is when this problem occurs. Can the truck randomly lose connectivity/programing with the truck? And then regain it? Because when it fails, if he leaves the key fob in the truck for an hour or two and keeps trying dozens of times, eventually the key icon pops up on dash and the truck restarts.

We've gone through the weak battery idea. The dealer tested it too. Seems to be fine. This is something related to that key icon.

 

Have you tried touching the FOB to the start button, then push the start button?

 

Did he happen to get the fob wet somehow?

 

No.

 

Yes, tried that, didn't change anything. The only constant is when it faults and won't start, the key icon does not come up on dash.