Steam damage to battery - possibly to logic board?

So a couple of months ago, I used to shower with my iPhone in the bathroom to listen to music. Not long after that habit, I noticed that my phone was dying earlier than usual and at odd percentages. By now, my phone lasts a bare 20-30 minutes off the charger before it's dead.

At the AppleStore, a diagnostic run on my phone said that the battery was in bad condition, but upon further research, I found out that battery issues could also be due to corrosion on the logic board battery connectors (presumably from the steam.)

Is this possible? Will getting my battery changed only solve half of the issue? Do I need to get my connectors cleaned as well?

Any advice would be greatly appreciated.

tl;dr - Steam probably damaged my battery. Could my battery issues be due to logic board battery connector corrosion as well?