Here is a summarized process for flashing the SM-T280.
Flashing a custom ROM voids your warranty (expired anyway), wipes your data, and carries a tiny risk of "bricking" (turning your tablet into a fancy coaster). However, the SM-T280 is notoriously hard to hard-brick because it has a built-in download mode and can be restored via Odin. galaxy tab a6 sm-t280 custom rom