If the smart key has been damaged can it drain the battery

Hello, if you truly have a "parasitic draw", which is a component still drawing power after the vehicle is shut off, then hands on diagnostic testing will be needed to measure the draw and then one by one remove fuses to see which system is causing the concern. Then, troubleshooting in that circuit can begin. A 2017 Accord does not have any common concerns for battery draining. Are you still under 3 years / 36,000 miles? You have a warranty then that can be helpful - see your local dealership in that case.

Additionally - *ANY* aftermarket add on accessories are the first suspect! This is not a common problem with these vehicles so some-thing is amiss here.