You need to refund and exchange your pass for a global pass or an ordinary ticket to the nearest French/German border point from where you are living in Germany.

This cannot be done on the community. Make a new request here (select Pass Refund and Exchange): https://eurail.zendesk.com/hc/en-001/requests/new.

First I suggest that you calculate if it is cheaper to buy normal tickets for the parts of the travel in Germany or to make an exchange of passes for the fee of 15 EUR. Then you also need to add the higher price for a 4 day global pass.

Below are the instructions how to make an exchange of passes. You must buy the new global pass and sent both your old pass number and new pass number to Customer Support. You will then get a refund of the price for the old pass less 15 EUR.

https://www.interrail.eu/en/interrail-passes/ordering-info/refund-exchange-policy