For self-purchased products intended for installation, should the original packaging (OVP) remain unopened?

Hi, I have booked an appointment with an electrician to install outdoor lights.

I ordered the outdoor lights (brand: slv) myself online. I unpacked all of them and checked for damages so there won't be any unpleasant surprises later.

But now I heard from someone that I was not supposed to unpack the lamps. If we provide the products ourselves for the installation, they apparently have to be in their original packaging, so unopened?

However, a few years ago I also had a cooktop connected, which I had unpacked and was already installed in the countertop. So what is correct now? Can the electrician refuse the installation?

Who orders not only may but must also unpack. The electrician is out of any warranty when you order the product of your choice.

Elli will never assume liability for [fremdware].

What kind of nonsense is that.. The kitchen fitter of my parents also wanted to explain that to me. We then told him that we would also like to buy the kitchen elsewhere. The electrician has to provide a warranty on the installation but not on the material if it does not come from him

Thank you all for your quick responses!!!