I have six Samsung Galaxy Avants that I can't do much with
You should be able to restore factory settings by flashing the Samsung stock ROM using the official Samsung tool named Kies. The procedure is explained here. Your device name should be Samsung Galaxy Avant G386T.

Alternatively you can try Odin. The procedure is explained here. You must be aware that Odin is not supported by Samsung. Using it incorrectly or flashing an incorrect ROM (for instance a ROM intended for another device) can brick (permanently damage) your phone.