First, Check its authenticity via its website or App , as per video shows.
Second, Fully charge the battery and then put it aside for over 12 hours.
Third, Check if it holds the battery which is 100% full, then do a through function inspection including buttons , touch screen, are working properly and sound quality is well.
Forth, Remove all previous user date from the app.
Fifth, Visual check and then clean the unit and pack it.