Hmmm...well, there's a few things you can try:
1. Did you charge it with the wall outlet plug charger that came with your Vox? If you plug it into the wall outlet (turned off) for at least 5 hours, you should be able to turn it on after that. After it's charged, hold the power button for at least 10 seconds. If nothing happens, then hold it again for 2-3 seconds. If it doesn't turn on - it could be an issue with the battery.
2. Pry off the back of the Vox and press the little button on the inside back. This will reset your device. I am thinking that this option may work for you.
3. Do a factory reset following these instructions:
https://www.mobileread.com/forums/sho...=factory+reset
If all of those options fail, you surely have a defective battery and would be entitled to a replacement.
Good luck!