Can I use my phone's repair mode instead of giving the shop my usual unlock code?

The repair booking asked for my unlock code. I am taking a Samsung Galaxy phone in because its charging connection is unreliable. The request might be routine, but I am uneasy about leaving access to family messages and photographs with it.

My phone has a Maintenance mode option. Samsung describes it as a separate account for repair handling that hides personal data, and recommends a backup in case repair requires a reset or storage replacement. [Samsung's guidance](https://www.samsung.com/us/support/answer/ANS10003675/).

I have not yet asked the shop whether it can do the planned checks in that mode. My brother says I am making the repair complicated; I think I am asking before arriving with a prepared phone and discovering the shop expects something else.

What would you clarify with the shop? I want to let it diagnose the fault, while keeping “we may need to test the phone” from turning into an unexplained request for the ordinary account.