How to put the shortcode in WooCoomerce login form?

You need to put the firemobile shortcode in the WooCommerce login form then it will automatically redirect the user to the my account page after login and the continue with phone button will disappear. 

Now to put the firemobile shortcode in the WooCommerce login form follow the below approach, 

You can do it in two way,

I)  apply the below code in your theme functions.php file 

function action_woocommerce_login_form_end()
    // make action magic happen here...    
// add the action
add_action('woocommerce_login_form_end', 'action_woocommerce_login_form_end', 10, 0);

II) you should override the WooCommerce template

You can override pretty much every WooCommerce template by copying them into a folder named "WooCommerce" in your theme.

This is documented at Template structure & Overriding templates via a theme.

The login and register forms non-logged in users see when they click "my account" are genetared by the template file /myaccount/form-login.php

So what you need to do is copy this file from the directory to your theme's directory (so it is /yourtheme/woocommerce/myaccount/form-login.php) and from there edit it as desired.

In this case, you will want to put the shortcode after the Login button.

Note: If you are using any Custom theme and the above solution not working for you then you need to contact the theme developer.