Nokia Lumia 1020 Black screen

[Philip_C]

Hi,

Sunday I picked up my phone from the table and the screen was black. It didn't respond to anything. Tried a soft reset without any result. Same thing for a hard reset.
Nothing happened to the phone. It was working normally one moment and just went dead.

Normally when you do a reset you can feel the phone vibrating but now it did nothing at all.
I thought it was the battery so I ordered a new one.
That came in, got installed and then I only got the windows logo that was blinking once when I hooked it up to the charger. That indicated the battery was to low.
Hooked the battery up directly to the usb cable to give it a boost.
Battery seems charged (I get 3.78V with my multimeter), logo doesn't blink anymore but the phone still doesn't react.
When I connect it to my computer I do get a sound notification that something is connected but it doesn't apear on the screen like it used to do.
When i do a reset, hard or soft while it is connected to the computer I hear it gets disconnected and immidiatly reconnects.
But still nothing is vibrating.

So what is wrong with the phone?

Is the screen/digitizer broken and does that control the vibrating also?
Not sure about this since the windows logo was lit up.

Or is the motherboard messed up but would it then still give connection to the computer and the sound for connecting/disconnecting?

Any suggestions on what I can do or try?

Thank you!