Droid Maxx Black Screen Of Death

Background, I have a Droid Maxx that I purchased/leased from Verizon, that arrived with 6-7.2. I downgraded to 6-7 and rooted. From the time of purchase the phone would reboot a few times a week. After rooting it began to reboot usually daily or many times a day. A week ago on Saturday it rebooted and began to loop from splash screen and back off. After many restarts it went into the factory recovery and no options would work and the screen forever went black. It has been charged for days, no button combinations work, except when plugged into the computer while holding the down vol it will load the hsusb drivers will sometimes load, and occasionally when connected to the computer or wall charger the green led will light. So I took the phone into verzion and they see the same results and attempted to charge it with both a cable and wireless, same results. So they shipped a new unit to me and before shipping this old one back to them I have a few questions for ones of you that may know the answer:

Anything I can do to restore it to stock? I assume no from my research
Will they discover its rooted?
If so what will be the resulting action?

Thanks for taking the time to read this.