Linko questa discussione per chi ha questo mio problema:
Random Restarts & Boot Loops On Your Galaxy Note 3? You’re Not Alone
e cito la parte che sospettavo...
“For some users, the boot loop occurs after updating to a newer software version on a new Note 3 and then installing their apps from the Play Store. For others, it happens when the device is intentionally rebooted while the SIM and microSD cards are in the device.”