Issues with Workflows to update records on different module

Hi everyone,

This is the first time I’m trying Workflows and I cannot make them work.

I need to run a simple automated task…
I have two modules inside a namespace. Module “Requests” and module “Inventory”. Inventory has a set of devices (records) that we own to borrow to different customers to run PoCs or tests, each of them with and exclusive Serial Number.

My idea is that when a user create a new request record, they should select one or more devices by its serial number and with a workflow, the selected Inventory records should be updated as “device in use”.

I’ve tried a lot of different ways to do this but the Inventory records were never updated.

Has anyone implemented something similar to this? Can you share which flow should I use?

Thanks in advance!