Change Register hyperlink to a button

Hi
I love the plugin but I’m having a hard time changing the register hyperlink to a button.

I looked at the after_admin_bar_render function in wpabi.php file and made the following changes but it didn’t seem to work.

$loginform .= '<div class="loginform">
<form action="'.wp_login_url().'" method="post" id="adminbarlogin">
<input class="adminbar-input" name="log" id="adminbarlogin-log" type="text" value="'.__('Username', $this->textdomain).'" />
<input class="adminbar-input" name="pwd" id="adminbarlogin-pwd" type="password" value="'.__('Password', $this->textdomain).'" />
<input type="submit" class="adminbar-button" value="'.__('Login').'"/>';
if($this->options['reg_link'])
{
   //$loginform .= '<button class="adminbar-button">'.__('Register', $this->textdomain).'</button>';
   $loginform .= '<button class="adminbar-button"><a href="'.wp_login_url().'?action=register">'.__('Register', $this->textdomain).'</a></button>';
}
$loginform .= '</form></div>';

https://www.ads-software.com/extend/plugins/wordpress-admin-bar-improved/