How to fix badly virused android device - Your device has been modified, software updates are not available

I have a Samsung Galaxy Note 10.1 that has been infected with some viruses really badly. After factory defaults, as soon as it connects to the internet it starts downloading some apps and advertisement windows pop up like every 10 seconds. Things I tried: - Installed AVG AntiVirus, CM serurity, Clear master - It helped me delete some files of the virus but did not solve the problem - Booted into recovery mode: - Wiped cache partition - wiped data/factory reset - Booted into Odin mode: - Product Name: GT-N8010 - Custom Binary: Download: No - Current Binary: Samsung Official - System Status: Custom - Tried to software update - Message: Your device has been modified, software updates are not available. What can I do to get rid of the virus and be able to software update normally?