Here's how I disabled mine
Alright, so the quick and dirty TL;DR answer for those of you who can't take another auto stop and just want to run out to your car and do this now (and it will take you 5 seconds):
Jam something in the button to keep it pushed down.
A guitar pick. A folded up receipt (that's mine), a bread clip...something thin and small that you can fill the gap with when you push the button down.
--DONE--
Now, for the longer "Is this idiot for real?" answer:
Yes, I'm for real. OBVIOUSLY, I'm not responsible for anything you do to your car, and you do this at your own risk, but just in case it SOUNDS like I'm just a ham-fisted idiot who thinks like a monkey and decided to "DUUUUUUH JUST JAM SOMETHING IN THURRRRR...." no, not exactly. Let me explain...
I'm an electronics engineering hobbyist, among many other things. I had originally wanted to tackle this project as an Arduino project, and eventually just program a chip and make a tiny board once I got the circuit down to the bare essentials. My idea for that project was to make a piggyback circuit that the wiring harness for that button would plug into. The circuit would read the state of the button light. If it was off, it would send a momentary high signal and wait until the light came on. The idea of this circuit was that it would ABSOLUTELY not cause any damage or do anything irreversible, and it would completely retain normal operation of the button. But it would essentially be like hiring an assistant to watch that light and always make sure it was disabled when you start your car.
One reason for the complexity, I thought, was because as you may have noticed, sometimes the system is actually disabled for a while when you start up. Colder mornings, I guess? I live in Florida, so we don't have many of those. But occasionally, I have thought to disable it and looked down, and it was already lit (disabled). But then it would turn off after a couple miles, and sometimes I'd remember and turn it off, and sometimes I would not, and my car would cut off. (I really hate this).
But the more I thought about it, the more I realized, there's already a circuit/program doing EXACTLY this with this button. Why double up the complexity? As a project, sure, it would be fun. But really, I just want the thing to turn off and stay off. I read many posts and watched many videos about how other car owners have found hacks to permanently disable theirs, and I found that other Kia cars have been disabled by simply jumpering the button wires to always be "pressed." The proponents of this method explained that in the technical manuals and schematics for their Kias, it seemed pretty cut and dry that a closed state on that switch would always put the program in "disabled" state. Makes sense to me. Basically, the entire program that controls the feature is a thing that says "enable the auto system UNLESS any of these things are happening..." and it listens for logic signals that are defined in the program. That button being depressed is one of those states.
That's where my testing started. I started simple: Tried holding down the button WHILE starting the car. Every time, the car would start and the light would come on in a fraction of a second. Definitely the desired result.
"Yeah, but it can't be good for a button to stay pressed. It's gonna burn something out."
I seriously doubt it. You have to understand, that type of button, a momentary button, is just like other control buttons in your car. Menu buttons, navigation, fan control, etc. They're not hard switches that have 12 volts running through them. It's not like the power for cruise control is running up to your button on the steering wheel, and when you press the button, it closes the circuit and powers your cruise control system with 12v. No, no, no... it's much more like all these buttons are like keys on the keyboard for your computer. They're sending super low-power, no-amp logic level signals. Do you think you would burn something up by holding down a key on your keyboard? No. You might tyyyyyyyyyyyyyyyyyyyyyyype weird, but it will never damage anything.
So, considering the car is in warranty and this is a really simple, cheap part, and I'm a bit of a tinkerer anyway, I decided to throw caution to the wind, trust my knowledge, and jam a receipt in the button to test it for a few days. I start my car up probably ~6 times on an average weekday. Maybe more on Saturdays...So, I have at least 25-30 starts, and so far, the system has never been enabled. I like those odds.
"OK, I trust you, stranger, but I don't want a folded up receipt jammed in my button. This car is my temple."
I hear you. I have never left anything in the car when I get out. I rub it with microfibers every chance I get, I only rinse with deionized water, I keep a spray detailer in my car just in case a bird poops on it. Trust me, the receipt sticking out of the switch isn't my permanent solution. That's my test. So...next steps?
I want to pull the switch out and see about replacing it with a latching button. I know that the little cluster that control is in is easy to pop out of the console, which itself is easy to pop out of the car. If you watch the "Sintger GT and Me" video of replacing the console with the door cup holder, you can see very well how this little module is a simple bolt-in box with a couple of wiring harnesses. I want to get a better look at it and see if the actual button switch inside is reasonably accessible. If it is, it's most likely a surface-mount that can be desoldered and replaced with a same-dimensions LATCHING type pushbutton instead of a momentary, as it is now. For those who don't know exactly what I mean, think of a clicking ball point pen. Push it once, the pen stays out. Push it again, it retracts. That's a latching switch. I would REALLY like to turn this switch to a latching type so I can push it once and disable the system for as long as I don't change it. Now, that MAY or MAY NOT work. Some testing is needed for that as well, if the switch is even accessible. The simplest solution would be to pull the console, figure out which wires are responsible, and jumper them. Only thing is, I don't want to lose the ABILITY to control the system. I just want to be able to set it to off and leave it that way.
One way I've thought of to semi-permanently but easily-reversibly jumper the system would be to run two wires to an empty location on the fuse panel and fuse it. As long as the fuse is in, it's disabled. Time to sell the car or whatever, and want to reset the button to its factory operation? Pull the fuse.
Anyway. If nothing else, I hope maybe this has been food for thought for others like me who want to come up with an elegant solution to this. I'm not saying a folded up receipt jamming a switch is elegant. But my car doesn't turn itself off anymore if I forget to push a button. And that's elegant enough for me until I figure something else out.