Black screen is often from a dead battery. Charge it with a wall charger for a few hours. The connect it to a windows PC (or windows MV on a linux PC) and use MfgTool to boot it to fastboot mode and let it charge for a few more hours. Then try booting it again. If it will not boot itself, try booting main and diags modes with MfgTool.
Report the results here.
There have been cases where a "fade to black" happens right after screen refreshes as an early symptom of a damaged eink screen (before a crack begins to grow). Hopefully it is just a discharged battery.