I woke up this morning to find my plugged-in iPad had only 2% battery remaining. It drained quickly and turned off while I scoped out in the System app things that might be awry.
Some time ago, I found and have been using some magnetic charging and data cables. They work great, for the most part. There's a little dongle you plug into your phone, tablet, keyboard, or whatever. The other end attaches to the charger or a computer, like any other USB cable. When you want to connect it, you turn the dongle and end of the cable towards each other, they connect, and it works.
I started doing this after the missus noticed her phone was getting ornery when the plug was torqued a certain way. The kids' iPads also suffer from frequent plug incidents, and this seemed to be an easy way to prevent iPads from hitting the ground as they forget to unplug before walking away, or to encourage charging when they return, as it's a little fun when the cable snaps to the dongle. I've been using it also on my iPad, which was more preventative of the loose port than anything.
Until this morning, no issues except when maybe the dongle leaves with the cable, instead of letting go. A tiny tip to loosen the magnetic grip solves that, and the motion is fairly natural, but sometimes the tip isn't enough, or you forget...then you notice the dongle is missing, and find it on the end of the cable.
Anyway, I took my dead iPad and plugged it into an Apple charger with an Apple lightning adapter. It turned the dead battery with a cable and lightning bolt, which seems to indicate a lack of charge, into the dead battery alone, which seems to indicate charging. Seems a little backwards, but the searches confirm this. After many hours of letting it try to charge, nothing. Still dead.
I tried many chargers, and many cables. Straight Apple cables, third-party lightning cables, and different dongle ends. Some would turn the lightning bolt and cable off, but none seem to add enough charge to let the tablet turn back on.
Until just now going into, going the second hour, it's been connected to an Apple iPad charger, with a dongle-magnetic adapter, and the evident charging screen. Still not turning on.
I've connected it to my MacBook Pro, which has had enough juice to charge it in the past. Same cable. Same evident charging screen. still not turning on.
I'm thinking about seeing if I can kick off a restore with the DFU.