Frame wont go invisible when frame.visible in script?

local frame = script.Parent
local sound = frame.Sound
local introText = frame.IntroductionText
local texts = {"Fight Until it is Over!", "Your Destiny Is Unfolding."}
local randText = texts[math.random(1, #texts)]
local flashSound = frame.flashSound

repeat wait() until game.Players.LocalPlayer.CharacterAppearanceLoaded
	
wait(1)

sound:Play()
for i = 1,100 do
	sound.Volume += 0.01
	wait(0.01)
	if sound.Volume == 0.2 then 
		break
	end
end


wait(2.7)
introText.Visible = true
introText.Text = "A Game By"
wait(1.4)
introText.Text = "A Game By Machiver"
wait(1.4)
introText.Text = "Thanks for Playing!"
wait(1.5)
introText.Text = randText
wait(1)
flashSound:Play()
sound.Volume = 0.6
frame.BackgroundColor = Color3.fromRGB(255, 255, 255)
wait(0.5)

frame.Visible = false

Write this on your line 34 : frame.BackgroundColor3 = Color3.fromRGB(255, 255, 255)

In line 8 you forgot to add :Wait() at the end. In line 34 change it to BackgroundColor3. And next time use task.wait() instead because it is faster and more efficient than wait().

local frame = script.Parent
local sound = frame.Sound
local introText = frame.IntroductionText
local texts = {"Fight Until it is Over!", "Your Destiny Is Unfolding."}
local randText = texts[math.random(1, #texts)]
local flashSound = frame.flashSound

repeat wait() until game.Players.LocalPlayer.CharacterAppearanceLoaded:Wait()

task.wait(1)

sound:Play()
for i = 0, 0.2, 0.01 do
	sound.Volume = i
	task.wait(0.01)
end


task.wait(2.7)
introText.Visible = true
introText.Text = "A Game By"
task.wait(1.4)
introText.Text = "A Game By Machiver"
task.wait(1.4)
introText.Text = "Thanks for Playing!"
task.wait(1.5)
introText.Text = randText
task.wait(1)
flashSound:Play()
sound.Volume = 0.6
frame.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
task.wait(0.5)

frame.Visible = false