I assume you cannot connect to Jolla (for account usage or creation, and “installing” developer-mode, which downloads the terminal app), because of outdated X.509-certificates for TLS / SSL (as in HTTPS).
- Do analyse, if this is the cause.
- If “yes”, try applying “olf (Olf0) (Olf0) / Guide - Fix certificate issues on SailfishOS · GitLab”
Detailed discussion at “[Guide] Fix certificate issues on SailfishOS”, but you need to read the whole thread!
I suppose whatever I did caused permanent damage.
I do not think so: Accidentally damaging the “onboard” factory image (used when performing a “factory reset”) is almost impossible.