Hi there and welcome
You said you tried with the volumne key butt it was not clear which one, so to be sure
Can you remove the battery to it
Then wait 5 minutes.
Put the battery back in, and hold Volume UP and Power.
Tell me if it then comes on please
Can you connect it to the computer and tell me please if this gets it to come on
I tried to call but got your voicemail?
But did the computer detect the phone?
ok, then we know the issue, It is the screen that has faulted. The data on it is ok, but the screen needs to be replaced
I am really sorry about this and you are going to have to return the phone to have it replaced. Once done though you will have access to your files on it again
I am really sorry about this, and if you have problems, or would like any additional information or assistance, please do not hesitate to let me know.