Anyone know what I might be charged for duty?

- for a brand new phone.
and
- used (not working phone) - for spare parts.

Thank you in advance.

In general it doesn't matter what's in the package - the Swiss customs only looks at the value including shipping on the outside declaration and will open if there's any doubt. Then they'll add 7.6 % value added tax plus a hefty Fr 20 or so administration fee.

Taking all this and shipping charges into account it's often cheaper to shop around and buy in Switzerland.

Richard