I'm currently trying to update it to IOS 18.5 after noticing today that my phone suddenly turned off randomly despite having 20% power. I turned it back on with some difficulty as it kept showing the white apple before the screen turning black, me retrying again, it showing the white apple again, and this repeating for about 3 times before I finally turned on my phone.
Everything SEEMED to work okay, but every 3 mins or so, it will keep shutting itself off, turning on the white apple, turning off it and repeating for serveral times before stopping abruptly, and I need to hold the volume and off button again to make it turn on.
its battery health is at 87% And it will turn off before the update even finishes preparing.