[wdihuwuhidhuw]

With the dummy, you're referring to sealed box which is different from wrong item received. It is not really a conventional idea to say that you received a dummy just in case you interpreted it that way.
If you dont have an OTP on the delivery, do DNA.
If you have an OTP, do EB (others will disagree but its very simple and still works in my experience)
If you want to use the more advanced techniques, you can find an item that has a similar weight and order that on a throwaway account, and claim you received that (wrong item received).
Even more tedious would be a sealed box as it would involve waiting for a dummy and sealing stickers from China, and on top of that a return process.
I would advise you to do the easier ones if applicable