I was in the same boat previously and was thinking about opening up my hd 8 to resolder the charging port like everyone had mentioned. However, I found 1 cable that seems to be able to charge it consistently while a lot of my brand new cables were not able to charge it. I knew it's wasn't the cables since I could use those same one to charge my other electronics that uses micro USB. Also, with the non working USB cable, “sometimes” when I slightly bend it towards the back it would charge very slowly. What I finally concluded was that the pins in the charging port were getting worn out and that it no longer make sufficient contact to charge the tablet. I ended up scrubbing the pins with a needle to remove any oxidation (yellow arrow side) to maximize contact, then I also added a very small piece of paper fiber to the flat side of the “D” port which helps push it to the middle a bit, see orange arrow ( you do not need much at all, and if you feel resistance when trying to plug the USB cable in then STOP and take it out and replace with an even thinner piece of material. I used a needle to kind of push it in or out). Now I could use any micro USB cable and it would charge quickly.
I figured I'll post this for everyone to try before replacing the USB port since the newer 8 hd seems to have the screen glued on and you might risk cracking the screen.
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