Electronic Massager No Power

This Battery powered electronic massager was no power. So I check the battery if it has charge and it is confirmed that it is in good condition . So I check the supply from positive supply of battery and it supplied 4.5 volts. But when you pressed the power switch it will not switched on. So I checked the power switch and it's not working. I replaced it with new one and the massager came back its display in its LCD display.