Even if it does not look like it is charging and even though it may be fully charged charge it using a different wall outlet than you normally do (a different room is best) for at least 10 minutes.
Do not skip that even if it is fully charged from you already plugging it in, it is important to do it.
It sounds like the firmware may be frozen try this and let me know the results hold the power switch for at least 60 seconds.
Try this at least 6 times.
The firmware can sometimes get frozen the same way that a computer will occasionally.
i had tried your suggested remedy to the last lettr but it did not work so i gave after up trying both with it on charge and not charging but fully charged .about 20 times .it was reacting to the on/off switch by the bottom line illuminating with the standard instruction on how to switch on and it disappeared when it was switched .I decided the program was working ok but the fault was in the screen. since all the rest of the screen was still in the same state as when i started. I have ordered a new Kindle .!!!!!
forget it .it is too much bother to think of replacing the screen. an exact replacement kindle is only £59. I have ordered a Kindle Fire. thank you for your efforts