TextBox Focus Issue in ASP.NET

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ASP.NET

I am developing a Simple Web Application in ASP.NET.
My First TextBox is set as ReadOnly.

So I want to focus on my second TextBox i.e. TextBox2.

I tried with the following codes.

protected void Page_Load(object sender, EventArgs e)
    {
        TextBox2.Focus();
    }

or

protected void Page_PreRender(object sender, EventArgs e)
    {
        TextBox2.Focus();
       
    }

or

protected void Page_Load(object sender, EventArgs e)
    {
        Page.SetFocus(TextBox2);
    }

protected void Page_PreRender(object sender, EventArgs e)
    {
        Page.SetFocus(TextBox2);
       
    }

but none of the code is working.
Cursor placed in TextBox2 by those code. but the cursor is not blinking.
So, I can't write in the textbox until I use my mouse to move the pointer and click there in textbox.
I need the cursor to be blink and be able to write at the time of page load.

Please suggest!