Mercedes SL engine wont start

Sounds familiar. Check your battery cables first. Are they clean and tight? A bad connection can cause all sorts of weird issues with the electronics and prevent the engine from starting. Check the voltage with a multimeter to ensure your battery has enough juice to start the engine. Did you check for any blown fuses?

When you say 'similar problem,' do you mean the exact same symptoms – complete non-start, engine light on, and suspected electrical issue? Also, where exactly would I find the relevant fuses to check, and what amperage should I be looking for?

Yes, exactly. Same thing happened to me. Ended up being a corroded battery terminal that was preventing enough power from getting through. Check the owner's manual to see where the fuses are and the amperage. Honestly, just take it to a decent mechanic. They will figure it out quickly. If it's just the battery cables, it shouldn't cost too much.

The battery cable connections were indeed the culprit. Cleaned and tightened them, and the car started right up. The repair cost was 155€, which included a diagnostic check and cleaning the battery terminals. Appreciate the guidance.