Thank you for confirming.
This was the last step you can attempt at the user level, and the persistence of the problem would unfortunately confirm an internal hardware failure.
These kindles really cannot be repaired economically. It is less expensive to replace it entirely: http://amzn.to/1NqtDmD
The base model is only $49 now.
However, you may still want to
be to contact Amazon kindle service directly, at 866\321\8851. Even if past the warranty, Amazon usually has very good customer service, and will often offer a credit/trade in toward a new or refurbished kindle model.
When you receive your replacement kindle, once it is registered and connected to wifi, all of your existing books/purchases will sync to the new kindle, so you won’t lose any of the content you’ve previously purchased.
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
I am only paid for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a positive rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately.