Etios ignition error

That's a tricky one. "Terminal 15 ignition positive interrupted" suggests a problem with the power supply to the ignition system. Since the engine won't start, it's definitely critical. Have you checked the fuse box for blown fuses related to the ignition circuit? Also, what about the battery terminals? Are they clean and tight? A voltage drop there can cause all sorts of weird issues.

Fuses all look good. Battery terminals are clean. Where exactly should I be looking for a voltage drop?

Alright, since the basics are covered, the voltage drop could be anywhere along the circuit. Honestly, tracing it without proper tools is a pain. Given the error code and that it prevents starting, it really does sound like a defective cable or plug connection. For the sake of your sanity (and your Etios), I'd suggest taking it to a workshop. That kind of thing can quickly spiral out of control and cause even more damage if you poke around without knowing what you're doing. It will probably be a relatively cheap repair.

Thanks for the advice. Took it to the workshop; faulty connector, exactly as you said. Cost me 95€, all sorted now.