Excluding my "end" problems whats the issues with this script?

I already know that my ends on my script are misplaced, the script isn't working regardless.

remote.OnServerEvent:Connect(function(player)
        if usingPower == false then 
            usingPower = true
            ifMaster(player)
                while usingPower == true do 
                    Endurance = Endurance - 1
                    wait(1)
                        if Endurance == 0 then
                            break 
                        end
                    end
        elseif usingPower == true then
            usingPower = false
            unMaster(player)
            end
        end

My ifMaster(player) and unMaster(player) I confirmed to work. its this specific script that the issue comes from. It does operate the ifMaster(player) function, but the usingPower value is not updated.