Device stuck in a "bootloop". Resolved after re-inserting battery
I got stuck in a similar bootloop last Sunday on my Samsung GS4 (i9505G), except instead of rebooting, it would power off.  Pulling the battery did not resolve it.  I had to plug it in to a charger.  The battery was at about 25% at the time.

Sadly, I do not know why that resolved the problem, but I wanted to post my reply in case it helps someone.