The light is on, and the liftgate is latched. There’s no obvious plunger-type switch. Is it built into the latch?
I went to Hyundai’s website, but as far as I can tell, there’s no information about this.
Not sure about the Hyudai, but I had a “door ajar” light on a Chrysler minivan and, after looking for the big pushbutton (showing my age), my guy informed me that there is a micro-switch inside the latch. I would have had to replace the entire latch mechanism, connections and door handle (to the tune of $150+). I opted to have him cut the wire to the switch. End of light, chime and all.
I think that you may run into the same situation.
Personally I wouldn’t have cut the wire. A little piece of black electricians tape on the instrument cluster can work wonders IF it’s just a little warning light. On my wife’s Nissan a big digital display lights up if a door is ajar.
BTW: A door isn’t a jar. It’s a door. 
You can get access to Hyundai factory repair manuals online at:
I figured it out.
It’s in the latch mechanism.
And, BTW, I looked at the Hyundai manuals on-line, and as far as I could tell, there was no information about it (but, those shop manuals are weirdly arranged - it might have be under something stupid like “safety.”)
Warning light and…I didn’t have enough tape to cover the dome light or muffle the damn binger!