Turn instructions into an action list

Turn the instructions below into a clear action list that helps me proceed one step at a time. Keep the list grounded in the instructions and context provided. Mark any missing information with [check].

What I am doing:
I am preparing to return a used item to an online store.

Instruction text or my summary of it:
{{ohje}}

Prefer a public instruction from the service or your own summary. Remove personal identity numbers, customer numbers, banking details, health information, addresses, and other unnecessary identifiers from the text.

My situation, without identifying details:
I want to know what to do first and what I need to bring.

Return in this order:
1. The goal in one plain sentence.
2. A numbered action list: step | what I do | what I need | which part of the instructions supports the step | what to check. Name the source with a short phrase or section title if it appears in the material; otherwise mark [check].
3. Deadlines, fees, and contact details only if they appear in the instructions provided. Otherwise mark [check].
4. Questions the instructions do not answer but that must be resolved before acting.
5. One small first step I can take now.

If the matter concerns rights, benefits, health, money, or binding terms, verify the action list with the original source or the service handling the matter before acting.