Take a look at the charge port. Does it look like there’s any debris in there? Sometimes a bit of debris gets in there, then jammed in really far and compacts like stone from the cord being plugged in. If so, you can use a really thin set of tweezers to carefully clean it out, and then spray it with some compressed air. You may have to scrape it out, so be very very careful that you don’t damage the port itself.
If that doesn’t fix it, then you’ve done everything you can on your end. The only other thing it could be is damage to the port, a bad battery, or a motherboard issue. All of which unfortunately you’d have to take to Apple.
The fact that it started after an update and a DFU isn’t working makes me think it’s probably the battery or motherboard, but hopefully cleaning the port fixes it for you.