I am sorry to hear about that problem. My name is***** am a computer expert with 17 years of experience and I will be trying to help you as good as I can.
Please do the following:
1. Find the power button on the back of your HDX, then press and hold it for 25 seconds. Ignore any onscreen prompts. After 20 seconds, your screen will go black.
2. Press the power button again, it should startup fine again now.
If it doesn't work, please just reply again and I will help you further on to fix your problem. That involves no additional costs for you, you can reply as often as you want until I was able to solve your problem to your satisfaction. If I was able to help you, I would very happy about a positive rating (select 3 to 5 stars at the right top of the screen and click "submit"), because only then I get paid by JustAnswer, which mediated your question to me as an independent expert.
Thank you very much and best regards,