Super glitchy script help? Return end?

This is a little inefficient.

Here are some of the errors I found:

For loop ends positioned improperly (loops inside loops)

AlarmMinor and AlarmMajor functions both fire when above 1000 (no upper restriction on Alarm Minor)

What I would do is use the Changed event of the NumberValue object to check the temperature every time it is changed. Then you won't have to wait 5 seconds to update.

currentTemp=game.Workspace:WaitForChild("TemperatureValue")
AlarmMinorS=game.Workspace.AlarmMinor
AlarmMajorS=game.Workspace.AlarmMajor
MainframeStatus=game.Workspace.MainframeStatus.SurfaceGui.TextLabel

local firethree = workspace.Mainframe_Status_Fire_Parts:GetChildren()
local mainframelights = workspace.MainframeLights:GetChildren()
local emergencylightson2 = workspace.EmergencyLights:GetChildren()
local lightson2 = workspace.EnteranceLights:GetChildren()
local lightsonfloor2 = workspace.EnteranceFloorLights:GetChildren()

local emergencylightson = workspace.EmergencyLights:GetChildren()
local fireone = workspace.Mainframe_Status_Fire_Parts:GetChildren()
local mainframelightstwo = workspace.MainframeLights:GetChildren()
local lightsoff = workspace.EnteranceLights:GetChildren()
local lightsofffloor = workspace.EnteranceFloorLights:GetChildren()

local mainframelightsthree = workspace.MainframeLights:GetChildren()
local emergencylightsoff = workspace.EmergencyLights:GetChildren()
local lightson = workspace.EnteranceLights:GetChildren()
local lightsonfloor = workspace.EnteranceFloorLights:GetChildren()

local state = nil -- current alarm level

currentTemp.Changed:connect(function() -- Changed event
    if currentTemp.Value >= 700 and currentTemp.Value < 1000 and state ~= 'MinorAlarm' then -- Between 700 and 1000 and not already fired
        state = 'MinorAlarm' -- Sets alarm level to Minor
            AlarmMinorS:Play()
            AlarmMajorS:Stop()
            wait(3)
            MainframeStatus.Text = "LavaBlast://Core_Status/Issue"
            MainframeStatus.TextColor3 = Color3.new(255, 85, 0)
            wait(3)

            for i = 1, #firethree do
                firethree[i].Fire.Enabled = false
                wait(0.5)
        end

            for i = 1, #mainframelights do
                mainframelights[i].Light.PointLight.Color = Color3.new(1, 170/255, 0)
                mainframelights[i].Light.PointLight.Color = Color3.new(255, 170/255, 0)
                mainframelights[i].Light.BrickColor = BrickColor.new("Orange")
                wait(0.5)
        end

            for i = 1, #emergencylightson2 do
                emergencylightson2[i].Toggle.Value = false
                wait(0.5)
        end

            for i = 1, #lightson2 do
                lightson2[i].Part.SpotLight.Enabled = true
                wait(0.5)
        end

            for i = 1, #lightsonfloor2 do
                lightsonfloor2[i].Light.PointLight.Enabled = true
                wait(0.5)
            end

    elseif currentTemp.Value >= 1000 and state ~= 'MajorAlarm' then -- Above 1000 and not already fired
        state = 'MajorAlarm' -- Sets Alarm Level to Major
            AlarmMajorS:Play()
            AlarmMinorS:Stop()
            MainframeStatus.Text = "LavaBlast://Core_Status/Major"
            MainframeStatus.TextColor3 = Color3.new(255, 0, 0)
            wait(3)

            for i = 1, #emergencylightson do
                emergencylightson[i].Toggle.Value = true
                wait(0.5)
        end

            for i = 1, #fireone do
                fireone[i].Fire.Enabled = true
                wait(0.5)
        end

            for i = 1, #mainframelightstwo do
                mainframelightstwo[i].Light.PointLight.Color = Color3.new(1, 0, 0)
                mainframelightstwo[i].Light.PointLight.Color = Color3.new(1, 0, 0)
                mainframelightstwo[i].Light.BrickColor = BrickColor.new("Red")
                wait(0.5)
        end

            for i = 1, #lightsoff do
                lightsoff[i].Part.SpotLight.Enabled = false
                wait(0.5)
        end

            for i = 1, #lightsofffloor do
                lightsofffloor[i].Light.PointLight.Enabled = false
                wait(0.5)
            end

    elseif currentTemp.Value < 700 and state ~= 'NoAlarm' then -- Below 700 and not already fired
        state = 'NoAlarm'
            AlarmMinorS:Stop()
            AlarmMajorS:Stop()
            wait(3)

            MainframeStatus.Text = "LavaBlast://Core_Status/Stable"
            MainframeStatus.TextColor3 = Color3.new(255, 255, 255)

            for i = 1, #fireone do
                fireone[i].Fire.Enabled = false
                wait(0.5)
        end

            for i = 1, #mainframelightsthree do
                mainframelightsthree[i].Light.PointLight.Color = Color3.new(255, 255, 255)
                mainframelightsthree[i].Light.PointLight.Color = Color3.new(255, 255, 255)
                mainframelightsthree[i].Light.BrickColor = BrickColor.new("White")  
                wait(0.5)
        end

            for i = 1, #emergencylightsoff do
                emergencylightsoff[i].Toggle.Value = false
                wait(0.5)
        end

            for i = 1, #lightson do
                lightson[i].Part.SpotLight.Enabled = true
                wait(0.5)
        end

            for i = 1, #lightsonfloor do
                lightsonfloor[i].Light.PointLight.Enabled = true
                wait(0.5)
            end
        end
end)