Won't start on battery after battery replacement. Will strt on charge

My friend brought me his macbook pro A1502 EMC 2835. It would run when connected to the charger but would not run on battery power. Screen said 100% charged and also said battery degraded. So I bought an ifixit replacement battery and installed. Installation went smoothly. Original battery was pretty bulged. Problem is, computer will not start on battery. It will start when connected to charger and said 58% and was charging (orange light) went up to about 65% After some smc resets and psomething reset it went to displaying 100% charged and and charge port is now green.

Is there anything I can try to fix this? Logic board problem? Would really like to try an fix this so I don't give it back in the same condition with a 90 dollar new battery in that won't work.

Thanks,

Roveer

Here is information from coconut battery,

As soon as I pull charger port, the laptop goes dead. Does not run on battery at all.

I'm starting to think this laptop had some liquid damage. I was cleaning the exterior where I found a lot of evidence. On my recent re-entry to disconnect the battery and remove the ssd I started to notice evidence that liquid had entered. I also noticed one or more very small compoents that had crud around them.

Now, I have watched my share of Luis Rossman videos and as much as I would love to learn board level repair I'm not anywhere near capable of doing that kind of work. So I now wonder about the options here. The laptop works on AC but I'm assuming my friend would like to to work on battery. this is a 16gb i7 variant. I did some poking around and it seems like replacement logic board are as expensive or close to the cost of an entire unit (looking on eBay). Does anyone have any suggestions on what path I should follow here? I guess for 200 bucks I could grab another laptop, switch (with great pain), the brand new ifixit battery and SSD to the eBay unit and that would give him a working unit. Or the replacement logic board hoping that I don't damage a connector in the swapover. Is this worth a 200 dollar investment? I'm guessing i7 and 16gb means probably yes. + the new battery. I'm open to suggestions.

My friend tells me that he has his "music" software on this machine and that's what he uses it for. I did find some kind of DJ software on here. Also, did a time machine backup before starting this whole process. Undertand I'm a PC guy with a fascination for apple products. I'm typing this on a 2013 imac (running windows of course).

Thanks for your input.