can I trade in a Iphone at an apple store even if it's not working?

You can, however the total amount that you can get is determined by the condition of the device(s). You may not get anything for non-working devices. Apple will be happy recycle those devices for you. You can always find out by going to the Apple Store and asking for the Trade-in value directly.

The other thing is that you can only trade-in one item for one purchase. If you have two items to trade-in to purchase one item, then you will have to receive the trade-in value for both items in the form of Gift Cards. After that use the Gift Cards (value of the traded-in items) to purchase your new Apple Device.

Axel F.

Try if you wish. The value for an iPhone that fails to work is almost certainly zero. Apple would accept the device for recycling.