Can a bad alternator cause a spike and ruin the starter and electrical system?

What is your question?

Took car in for a battery light. Mechanic determined it was the alternator. Upon further diag they said the starter is bad too and the alternator may have "spiked" and caused the issue with the starter. Replaced alternator, starter and battery. Now the remote start does not work, error on dash says hood ajar, it's not. The horn sounds like a mouse and the airbag light is on. I took it back in for them to look into the remote start and when they couldn't figure it out I was leaving and noticed my headlights aren't on but interior lights are on and the light on my dash that says my lights are on is on as well.