Source: https://www.reddit.com/r/JBL/comments/etuedm/jbl_live_650btnc_will_not_turn_off/
Solution by Silly_Biomolecules:
I had the same problem on a 2 month old set of JBL live 500bt headphones. What worked was this series of steps:
(1) factory resetting the device by holding the + and - keys at the same time while the headphones were on
(2) while the headphone started the pairing process (blue light and pairing noise), I plugged it into my laptop usb port
(3) shut down the headphones
I think this is bug is caused when you plug the headphones into a computer while they are still powered on. Just a hunch. Hope this works for you lads