If the device loops repeatedly at the logo screen after showing a "PASS!", boot into Recovery Mode manually (Hold Volume Up + Home + Power when off). Select Wipe Data / Factory Reset , confirm the choice, and then choose Reboot System Now .
Flashing a full stock ROM will wipe your internal storage completely. Back up your photos, contacts, and documents to a cloud service or a microSD card. samsung galaxy tab a6 sm-t285 firmware download