Updating the total quantity:

Go to the Inventory app in Odoo 17.

Navigate to Products > Products.

Search for the rental product you want to update.

Click on the product to open its form view.

In the product form view, you should see a section for inventory.

Update the "Total Quantity" field to reflect the correct quantity available for rental.

Adding serial numbers:

To add serial numbers for rental products, follow these steps:

Go to the Inventory app.

Navigate to Products > Products.

Search for the rental product.

Click on the product to open its form view.

In the product form view, go to the Inventory tab.

Look for a section related to serial numbers. If you don't see it, you may need to enable serial numbers for the product.

Enable serial numbers if necessary, and then add the serial numbers for the available units of the rental product.