To repair or not repair. Fix it or replace it?

I need some advice/input. My 2011 MacBook Pro (A1278) has been a pet project for me and I have upgraded several parts: hard drive, RAM, keyboard, hard drive cable, dc-in, etc. Then my screen got smashed so has to be replaced. I would do it w/o hesitating but there has been an issue w/ the battery that I cannot figure out. The battery is not recognized so I can only use it while it’s plugged in. I tried everything possible on the software side. After none of that worked I replaced the battery, the charger/adapter the magsafe dc-in, the sleep sensor, and none of that worked either. I know this machine has been extended well past its years but I can’t afford to buy a new macbook right now and I need to be careful and conservative with my money. (Not to mention I dont like that I can’t open up new MBP to do simple repairs). I want to know what you all think about my options and what you would do. At this point the options I am leaning toward are (1) getting a fairly basic PC that I can immediately upgrade w/ RAM, maybe a hard drive, and (2) fixing my mbp screen and try to keep extending its age. I hesitate to do that because 1) a new screen is $300 which could help pay for a chunk of a new machine; 2) i wont know how much more i can get out of that machine and 3) needing to be connected to an outlet just sucks.

I welcome and and grateful for all advice, tips, suggestions, other points of view, and anything else you can throw at me.

Thank you so much!