Why is my Mac opening to the home page and then closing and repeating

It can be tricky getting the timing correct to enter any of the special boot modes like Safe Mode. You usually want to press the key(s) immediately after the startup chime or within a second or two of powering on the laptop if you have a newer model which doesn't chime. If the Caps lock key will light up, then press it so the Caps lock LED is lit during the boot process. When the Caps lock LED goes dark it signals the beginning of the boot process, then hold the left shift key for Safe Mode. You can also hold the power button until the laptop powers off so you can start from a cold boot.

Please don't forget the rest of my previous post.

Try booting into Safe Mode which will disable Startup & Login items as well as deleting some temp and cache files among other things. If Safe Mode works, try rebooting normally. If a normal boot doesn't work, then you may need to disable your login items while in Safe Mode. FYI, the display may flash or flicker due to the very basic video driver used in Safe Mode.

It would help if you could provide more exact details on the boot and login process. Is the progress bar still on the screen when it reboots? If so, how far along is the progress bar? Or does your Desktop show up when the reboot happens?

Is Filevault enabled?

Do you have more than one user account? If so, try booting into the other user accounts. If this works, then let me know as you may be encountering an odd macOS user account bug.

How do I get to safe mode if the computer keeps repeating the opening but won’t open

Tried to open in safe mode but it didn’t work. What do I do next?