This post is a little off the beaten path from my regular iPad posts, but I wanted to do something a little different for DIYers who are interested in getting their feet wet with some repairs of a relatively inexpensive tablet. In this case a Kindle Fire I picked up for $25 with the dreaded battery too low to charge message.
Indeed the Kindle was not charging, when I attempted to power it on it briefly flashed the battery was low then went off, the orange charging light would not come on. I figured since the Kindle has a notoriously weak charging port it was likely that was broken, so I followed the excellent instructions from iFixit for the teardown to remove the motherboard for inspection. Not only was the charging port loose, it was completely detached!
A close look at the charger port attachment shows it is indeed very poorly designed for constant plugging and unplugging, and probably heating and cooling. There are two metal attachment prongs on the charging port which fit in corresponding holes in the MB to hold the port. There are two flush solder points for power on either side of the port (the design would have been significantly better if these two points were through the board and not soldered on the surface), and five micro pins.
The solder looked to me to be brittle, and likely just detached after heating/cooling, up/down motion of plugging and unplugging the charging cable, the whole port just pulled off the board - a combination of poor design and bad solder.
So I cleaned up all the contact points, I put a tad of flux on the power points and pins, and with a bit of fresh solder and my iron hot, reattached everything.
The end result, the Kindle charging as it should. Hope this quick guide is useful to anyone else with the no charge problem, if you're at all handy with a solder iron this fix is not as hard as you would think. I rooted it, and then flashed Android - but that's another story.