My MacBook Pro in a reboot loop
My MacBook Pro starts and then in about 20 seconds reboots itself,
Question marked as
See if you can Boot into Recovery (Command R) and from the dropdown menu: Utilities> Disk Utility> run the First Aid on your Macintosh HD. If errors are found and repaired, run again until no errors reported.
Recovery: https://support.apple.com/en-us/HT204904
You can Try a SafeBoot https://support.apple.com/en-us/HT201262
Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Then reboot as normal.