Thanks for highlighting this. I just now read the podcast transcript at https://www.faa.gov/podcasts/the_air_up_there/fly-safe-lithium-batteries
At 5:10 minutes in, Robert Ochs, manager of the fire safety branch at the FAA’s William J. Hughes Technical Center, makes a distinction between devices you plan to use during the flight and those you do not plan to use:
“If you know that you are bringing a device that you won't be using during your trip, it's actually best to have it at a lower battery level. So, if it's at 30%, say, or lower, it's less likely to undergo thermal runaway and the reaction would be less severe. Another thing to do would be to not charge it. So, if you have a device that is off, but you're still charging it, it could also go into thermal runaway in that situation as well. So, it would be best to just keep it powered off and also not plugged in.”
Plus the importance of immediately notifying the flight attendant if a lithium battery device is overheating (signs given in podcast) or has become stuck in the seat mechanism.