1. Download the Firmware file (e.g. from www.sammobile.com)
2. Download Odin v3.10.7 Tool on your PC
3. Start Odin Tool
4. Reboot the Tablet in "Download Mode" (press Power + Volume Down Buttons)
5. Connect the tablet via USB to your PC
6. Select AP Option in Odin and brows for the Firmware file
7. Make sure the "Repartition" Option is NOT ticked
8. Click the Start button and wait a few minutes
When the message "Added!!" showed up I closed Odin and the tablet was agin up and running and malware free.