Sounds like a definite hardware failure. Does your Aristo have LG Backup installed? Might be a warranty claim. I'd get online or call tmobile from another phone.
Have you tried to do a hard reset?
Hard reset: (depends on your device)
press and hold:
The other way was to removed the batt... but i am sure you dont have that option.
Sorry to hear about your phone! If it still has not come on yet, I think we are going to need to do a warranty replacement as long as it is still under warranty. Let us know if you still need help!
Hey there! Did you end up having to replace your phone or were the steps the others here provided helpful?