Default [Q] HTC One won't start and won't charge

Hi everyone. I had my phone at about 50% charge. I turned off the screen and slipped it into my pocket. Just now, I tried turning it on, and it won't turn on. I figured the battery must have drained itself so I plugged in the charger and the light won't turn on. I then pressed down the down volume and the power button and it went into bootloader. From there, I pressed "reboot" and it again went dark. Now I can't even get it to start into bootloader. Even if this phone is dead, is there any way to retrieve the files stored on it?

Also, when I plug my phone into a USB, I get a message "USB device not recognized"
Does this mean it is still alive?