An 8 year old boy can only be expected to be so careful with the micro-USB charging port on his Kindle Fire HD (2013). Actually, I'm surprised it lasted as long as it did (he was 6 when he got it!). After a month-long cross-country road-trip, his Kindle would no longer hold a charge.
I used your tear-down guide:
I'll be honest - after determining the micro-USB port and ribbon cable were likely to blame, I went about trying to find a replacement elsewhere (ebay, Amazon). You had the best price. And I reasoned that even if it were a few $$ more on your site, I would have bought it here, as you provided a great service in the tear-down guide.
In examining the ribbon cable, it appeared a trace or two had been compromised by bending, so I decided to replace the whole assembly, rather than attempt to solder a new connector. The connector itself had broken off the retainer.
It was an easy repair. I came close to stripping the infinitesimal Torx screw heads - as I didn't have a tool specific for those and used a small flat-blade screwdriver. It only had to work once, I reasoned. :-)
Get the whole assembly. It was $10. Sure, I could have saved $5 by attempting to reuse the ribbon cable, but, like I said, it was likely part of the problem. Best to take the quicker route.
I loved the quote on your Spudger tool: "Repair is noble." That it is.