I have a similar issue. Phone has been working fine for almost two years now and all of a sudden after trying to type in my PIN to access my Private Space, the screen blacked out and became unresponsive then rebooted saying unable to load Android Operating System, if you see this message your data is likely corrupted.
I only have the option to Reboot or Factory Reset. I was able to access Rescue Mode and from there go to Fastboot but I've already rebooted several times and now waiting for it to reach full charge. Currently at 65% but phone was under 25% when this happened.
Not sure what to do once I access Rescue Menu or Fastboot Menu.
I typed the PIN wrong the first time and halfway into typing it a second time, it froze. I've only accessed the Private Space maybe twice before.