I have an older Kindle Fire HD. Recently one of my apps stopped working. My device is currently running on version 8.5.1 and the update button is grayed out and the app developer says this app is equivalent to android 5.0 and this device is too old to run this app. The app I am interested in is just to read books! Thanks for any advice which you can offer or should I contact to Amazon Kindle Support Phone Number at 1-866-947-8499 for best tech support.