3:Do not mix alkaline,standard (carbon-zinc),or rechargeable(Ni-Cd,Ni-MH,etc.)batteries. 4:Alkaline battery have expiry time ,please make sure the battery are valid. 10.Reset the unit Take away one pcs battery from walkie talkie battery compartment,then hold the Menu button and Lock button together meanwhile put back the battery to walkie talkie battery compartment in right polarity,the unit will turn on and display character “8” ,at this time ,release the buttons.