Samsung Galaxy S7…
Initial problem was "green light – black screen" issue.
I did a lot of web search; went through MANY options of different button combination recovery boots, which brought me to the famous "no command" screen many times, and many unsuccessful reboot attempts.
Sometimes, the dead robot – exclamation mark – "no command" screen would lead me into the options screen. I cannot lose my data, so I did not choose factory reset. Instead I chose ‘reboot’.
Selecting ‘reboot’ leads to the phone continuously restarting the initial Samsung Galaxy S7 screen, but would not lead to the animated "SAMSUNG" logo, it would just restart again to the initial Samsung Galaxy S7 screen.
In the middle of this continuous restarting, I disconnected the battery cable clip (with charger plugged in.)
This caused the phone to restart with the lightning bolt charge indicator on screen, at which point indicated I had 82% charge.
Now the phone is off, and is charging with the red light on, as if everything was normal.
IMPORTANT NOTE, I have reached this stage before, and when the green light indicating full charge came on, I reconnected the battery cable clip, and pushed the power button to turn on as I normally would. The phone started with the initial screen, and then DID proceed to the animated "SAMSUNG" logo, and one time even got me to my pin entry, but then died and went back to not restarted properly.
FINALLY, MY QUESTION, now that the phone is in a "normal" state of charging, what should I do first when the green light comes on to indicate full charge?
Connect battery cable clip again? Try to Power button Volume Down button for safe mode? I seem to be close to a successful restart again, and am unsure of the best procedure.
Also, could simply replacing the battery be the solution?
I cannot express enough my gratitude to any advice anyone out there can provide. Thank you immensely!!