Hello Bernie Nimer,
Thanks for clarifying. Since your Surface Pro 7 powers on and reaches the Windows 10 sign-in screen, it sounds like Windows is having trouble completing the sign-in process rather than starting up.
Before trying the boot-repair commands suggested earlier, I'd recommend checking the following:
- When the screen goes black, press Windows + Ctrl + Shift + B to reset the graphics driver. The screen may flicker or you may hear a beep.
- If that doesn't help, try starting Windows in Safe Mode. From the sign-in screen, hold Shift while selecting Power > Restart, then go to Troubleshoot > Advanced options > Startup Settings > Restart and press 4 for Safe Mode.
If Windows loads successfully in Safe Mode, that would help narrow the issue down to a possible driver or startup software conflict.
Could you let us know whether Safe Mode loads successfully, or whether it also gets stuck at sign-in?