[AC Question]

Some time ago my moto g (2014) - which had overall impressed me as a phone - just died one night, I thought had run out of battery, but in actual fact had only recently been fully charged, and would never boot again past the splash screens.
If I do the various button holding down combinations suggested online for 30sec to 2min plus, all I get is "powered by android" screen or the Motorola splash (moving world pics) followed by a dark black screen ( you can see the led backlight making a glow but it's basically an all black screen.
It won't connect to PC, it will seem to charge from usb on pc or mains, but I can never get past this point, cannot get any sort of android boot/system options or the sick android - none of this seems reachable.
I had to just grab another phone to work, but I did like this one and want it running again. How can I get over this point ? There must be some way - even to install update or new rom???
Thanks