The specific operation steps of replacing the U shield and reselling the invoice are as follows:

1. Confirm the U shield model: Before replacing the U shield, you need to confirm whether the U shield model matches the model supported by the financial system. Different banks or enterprises may use different U shield models, so it is necessary to confirm the U shield model.

2. Update the invoice information: after replacing the U shield, you need to update the invoice information to ensure that the invoice information matches the information supported by the financial system. This can be done by modifying the date, company name, invoicer and other information on the invoice.

3. Replace the U shield: After confirming the U shield model and invoice information, you need to go to the bank or corporate finance department to replace the U shield. When replacing the U shield, it is necessary to provide the old U shield, new U shield model and invoice information, and the financial department will check and verify it to ensure that the U shield model is correct and the U shield has not been damaged or lost.

4. resell the invoice: after replacing the u shield, you need to resell the modified invoice information to the financial system. This can be done through the invoice management module of the financial system. The financial system needs to identify the header, date, company name, drawer and other information of the invoice and update the corresponding invoice information.

the above are the specific steps to replace the u shield and resell the invoice. In practice, it may be necessary to make appropriate adjustments and modifications according to the financial system and process of the enterprise.