Phone won't power up after fully recharging to 100%

Phone is less than a year old. After accidentally letting the battery go completely dead, I put it on charger and got a different kind of screen indicating the battery had 0% charge. After a few hours it was up to 100%. Then I sought to get a normal looking screen by hitting the power button. Screen has been blank ever since. I tried removing the battery for 30 seconds and put it back. Still nothing. Do you understand what this does to user confidence in your machines? Utterly unreliable.