[Stl-986]

This could be debated as much as which oil brand is best or which leg goes into your pants first.

Disconnecting the positive cable 1st removes the possibility of a short.

While I do agree, disconnecting the negative cable from the terminal is best practice and the way I do it, it doesn't mean removing positive cable from the terminal 1st is wrong or bad. Removing either cable from the battery removes power to the car.

Back to the issue at hand though, removing positive cable from the battery will not cause a short or cause any electrical issues...ASSUMING the person didn't cause a short while lossening the bolt/nut that secures the cable to the battery (this is why you SHOULD do negative 1st).

My bet is that if anything happened there is a blown fuse somewhere and....we dont have all the information to determine the exact issue, we can only pass on recommendations of what to check as the most likely culprits that COULD be the issue.

The flickering lights described appear to me to be exactly like someone trying to wiggle the cable off the battery (either terminal) and the cable connecting/disconnecting fromt he post as part of this. Sounds perfectly normal to me cause a short would cause lights to NOT work. VERY common on top posts that crimp their sides to the post for ANY car.