iPhone XS Max only shows red battery charging indicator for a second

I have an iPhone XS Max that died mysteriously a couple of months ago. I had everything synced in iCloud so I’m not worried about the data, but I’d like to get the phone working again if it’s practical.

I spent a lot of time in the pool in the couple of months before it died, so it may be water related. It never fell in or was submerged, but there was a lot of handling it with wet hands. I thought it was waterproof but…

One day it just died. Black screen, no response. At first when I would plug it into my Mac the computer would see it, but then that stopped too.

After a month or so of sitting on my desk I noticed that some odd shiny copper-colored marks appeared at the edges of the screen, like an internal layer is delaminating:

Weirdly, if it sits on my desk for a week or sun until the battery is thoroughly dead and then I put it on the wireless charger, it lights up with the red “battery too low to turn the phone on” icon. This stays on for a few minutes, then it goes totally dead again.

What could be causing this, and how can I fix it?

Edit: I received an automated email suggesting I improve my question to help the community solve my problem.

1) Explain the troubleshooting steps that you have already tried. The more thorough your explanation, the more likely you are to get a helpful response.

Other than charging it, letting the battery die, and charging again (wired and wireless), there’s not much I can do. I’ve tried holding the side buttons to force a shutdown, and restart, but that has no effect. I would love suggestions to try.

''2) Improve your formatting and grammar. Use wikitext to format your question, especially for lists. You can learn more here: Wiki Formatting And Syntax''

I don’t think there’s an issue here.

3) Add a photo. A picture's worth a thousand words, and can help explain what's going on.

There’s not much to see other than the small marks under the glass that are already pictured. I can’t get the iPhone to show the red battery indicator at the moment, but it looks like this:

I’m not sure how to improve this question. I would welcome any suggestions. Thanks.