Battery Draining Quickly, I think a cheap Lightning connector caused

So I have an iPhone 6s Plus. Battery Health says 82% and performing at normal peak performance. The phone has been fine since I've had it. Pretty good battery life. Felt normal anyway. Up until the other day.

I, regrettably, bought one of these mini fans that runs off of your phone. Not this exact one, but they looked the same. Link to Fan. I plugged it in and the fan worked for a few seconds. I unplugged it. Then later I did it again and the fan started to turn and then stopped. Never to work again. I just assumed the $3 gadget was crappy and didn't expect much anyway.

After that, or at least that is when I think it happened, I noticed my phone was acting funny. The first thing I noticed is when I plugged it in to charge it, it wouldn't start charging (this was with an aftermarket, but MFi certified charger and cable that has always charged and synced just fine). I eventually got it to start charging using the standard Lightning cable that comes with the phone.

After that I noticed the battery draining rapidly. And inconsistent. It'd go from 30% to 15% in one big jump. I'd plug it in and it would continue to drop down several percent before finally going up again. And so on and so on. The inconsistency and big drops seem to have gone away, but it still drains quickly.

I can't say 100% that the fan caused it, but the timing suggests that it was the culprit.

To try and fix it, I did the following:

1. Hard reboot.

2. Tried to clean out the Lightning connector port, just in case something was in there.

3. Upgraded from iOS 10.3.3 to iOS 11.3.

4. Restored the phone to stock settings and then restored from a backup.

And the battery is still draining quickly. Roughly 10% per hour when I'm not doing anything with it (bluetooth off, WiFi on and connected). Just unlocking the screen here and there. When actually doing tasks (Apollo is the most used app), the battery goes down at least twice as fast. Even if just the screen is on/unlocked.

Location services is on, but only a few apps and none running all the time. All other settings that I can think of have been set to maximize battery life.

I was already considering replacing the battery, but I have a feeling that won't fix this issue. Is there another part that I can buy and replace that might fix it?

Thanks in advance.