Chosen Solution

My brother attempted to downgrade the firmware but after he installed the firmware the phone shuts off and started bootlooping.

If i were you i would try flashing the stock firmware Here is a link for www.getdroidtips.comThen when you have confirmed the phone works check the file you flashed and your phone for region compatibilityand please edit the question addin: The firmware you used The region of the phone (or just where you bought it) The tool(s) used for flashingGood Luck!