I checked the information about trading in and I don't trust it actually

If the iPhone you want to trade-in is damaged, your trade-in value will be less. All figures are up-to, in your case it's up to 150 $. I suggest you bring your iPhone into an Apple Store for a validation to see how much trade-in value your phone will give you. If Apple decides that your phone won't give any value, they will recycle it for free.

You can also sell your iPhone on your own.

The online quote is an estimate. As the fine print says, final determination of trade in value is always dependent upon physical inspection of the device. It’s that way with any for-profit recycler/buyer. Nobody guarantees a trade in value without seeing the device for themselves.

Since your microphine and receiver are not working, it is not unexpected that the actual trade in value is zero. The recycler cannot resell it, and the cost to fix it is more than its fair market value, so it’s actual trade in value is nothing to them.