T 9 is ok to spray on electronic circuits to help against corrosion. T 9 is not conductive and should not harm electronics. Because it leaves behind a waxy non-conductive coating it might interfere with electrical
contacts. So if your torches don't work probably you can "fix" them by removing the waxy coating on any metal contacts (batteries, contact springs, switches, etc.). You can just try scraping it off or you might try mineral spirits (stay outside in fresh air) to remove the waxy residue of T 9.
In future don't spray T 9 on areas where electrical
contact is required (switches or battery contacts). Covering these areas with tape might work.