<% if current_user.liked? likeable %>
  <%= form_tag unlike_path(likeable_type: likeable.class.to_s, likeable_id: likeable.id), method: :post, remote: true do %>
    <% button_tag class: 'btn btn-block liked' do %>
      <%= fa_icon 'thumbs-up' %> unlike
    <% end %>
  <% end %>
<% else %>
  <%= form_tag like_path(likeable_type: likeable.class.to_s, likeable_id: likeable.id), remote: true do %>
    <% button_tag class: 'btn btn-block', style: 'cursor: pointer' do %>
      <%= fa_icon 'thumbs-up' %> like
    <% end %>
  <% end %>
<% end %>

<% if current_user.liked? likeable %>
  <%= form_tag unlike_path(likeable_type: likeable.class.to_s, likeable_id: likeable.id), method: :post, remote: true do %>
    <% button_tag class: 'btn btn-block liked' do %>
      <%= fa_icon 'thumbs-down' %> unlike
    <% end %>
  <% end %>
<% else %>
  <%= form_tag like_path(likeable_type: likeable.class.to_s, likeable_id: likeable.id), remote: true do %>
    <% button_tag class: 'btn btn-block', style: 'cursor: pointer' do %>
      <%= fa_icon 'thumbs-up' %> like
    <% end %>
  <% end %>
<% end %>

Set thumbs down to unlike
fix: Set thumbs down to unlike
