Allwinner a33 h739 firmware ???

Hi
i have problem with tab "bootloop in logo" i what to hard reset but that tab have only 2 bouttans "home" "power.on/off" so i have no chose only to flash it any one can help me ?

Modele: I.t.work tm707
mainboard: H739-mainboard-v4.0.0
cpu: Allwiner a33