What access do you need to fix a Magento bug?
Ideally three things: (1) SSH or deploy access (or your DevOps contact), (2) an admin login, and (3) Git repo access so fixes are version-controlled. For a quick diagnosis we can start with just the error string and a screenshot. We sign an NDA on request and access is removed the moment the job is done. We never ask for card or payment-gateway secret keys.