[mothered]

I have agreed with returning the malfunctioning item to the company

Or to send a sealed cheap new item similar to the one that I have to return and hoping that the company will just check (taking advantage also about the fact that is near the Christmas) the package has just arrived to their warehouse without opening it.

The problem Is you've stated that the Item Is nonfunctional, which will give the company reason to check your return.

since the item weight almost 60g I was just planning of boxing them

I was thinking of sending the package with the package of the item empty but what if the courier wants to open it and inspect it?

To box them, you'd need to show signs of tampering and given the carrier Is aware that It must be Inspected, It will be Immediately noticed without opening It.

Do not seal your shipment as the courier must inspect the contents.

I assume they're asking you to take It to a DHL Service Point? If so, It will be checked.

To be honest, you should've researched more Into the carrier and their return policy, as well as selecting a method & Item suited against your (researched) findings.

For example, you could've used the sealed box method, thereby the carrier will only check that the box Is enclosed & sealed, and the same applies to the company- there's no reason to open and check If the Item Is enclosed on (what seems to be) a return In Its original state.

During a SE I have agreed with returning the malfunctioning item to the company

Please elaborate further on this.