Can't boot in normal mode, only in safe mode
I have updated my Mac mini with a new SSD hard drive. After the update, My Mac couldn't boot in normal mode, only in safe or using an USB boot disk.
I have tried booting from the new hard drive, and from the old hard drive, and always the same, it start to boot, and suddenly the Mac restart again. Some times, few seconds after reboot, other times, some minutes later, so it's very strange.
Using safe mode, I can boot from the new hard drive, and from the old hard drive, both have operating system, and the Mac never reboot.
I'm using macOS Sierra (10.12.5) in both hard drives.
I have 16GB of RAM, I tried to install the original 8GB of RAM that came originally in the Mac, and happen the same.
I checked the RAM booting in DIAG mode, and left the system checking memory all the day, and RAM seems good.
Furthermore, I have checked the MAC using TechTool Pro, and Etrecheck, and everything seems good, no problems detected.
I don't know what could be the problem, because when the system reboot while booting in normal mode from hard drive, never reboot in the same point, like I told you, it reboot in randomly way.
I don't know what to do.
I have removed the NVRAM booting pressing Cmd+Alt+P+R, and no solution.