Default [Q] [q]note 3 probems

Hello, I'm newbie here, I've bought Note 3 few months ago and I'm facing this problems today and any answers will be appreciated and if i got my probem solved then i will donate some money to problem fixer First of all i will make list of certain problems i am facing
1.When i start my Phone the i see the circle like No entry sign instead of network Bars and when i do software update it says that registering device and then processing failed
2.when i start playing with it then it automatically reboots and then struck at bootloop cycle reboots( phone starts and appears that Samsung Galaxy Note III n9005 and then again restarts and again and again )
i cant leave my phone like this and i cant figure out what problem it has
I'll Donate 20 to 30 $ for sure
WILL INSTALLING CUSTOM ROM SOLVE IT ??

POST SCRIPTUM : I'VE TRIED MANY FACTORY RESETS AND AND WIPED CACHE AND IT CANT SEEMED TO HAVE HELPED SO I HAVE NO WARRANTY HERE as I'VE IMPORTED IT
SO PLEASE HELP, HOPE ANYONE WILL HELP ME