Rockstar, 168 bytes

Listen to B
Knock B down, down, down
Put B into X
Build X up
say "╔"+"╦"*B+"╗"
While X ain't nothing
say "╠"+"╬"*B+"╣"
Knock X down

say "╚"+"╩"*B+"╝"

Copy Paste it here!

I was inspired by Shaggy from this comment.

Here's the real rock song (sort of).

Listen to the bars
Knock the bars down, down, down
Let the end be the bars
Build the end up
Shout "╔"+"╦"*the bars+"╗"
While the end ain't nothing
say "╠"+"╬"*the bars+"╣"
Knock the end down

Shout "╚"+"╩"*the bars+"╝"
Let the prison be gone

Rockstar, ¹⁵⁰ 104 bytes

Listen to B
let B be-3
X's-1
say "╔"+"╦"*B+"╗"
While B-X
say "╠"+"╬"*B+"╣"
let X be+1

say "╚"+"╩"*B+"╝"

Copy Paste it here!

-46 bytes from Shaggy.

I was inspired by Shaggy from this comment.

Here's the real rock song (sort of).

Listen to the bars
Knock the bars down, down, down
Let the end be the bars
Build the end up
Shout "╔"+"╦"*the bars+"╗"
While the end ain't nothing
say "╠"+"╬"*the bars+"╣"
Knock the end down

Shout "╚"+"╩"*the bars+"╝"
Let the prison be gone