I’m sorry to hear of your troubles. I have had my share of computer problems too and it is pure misery.
One suggestion? Perhaps find a local “computer guy” type shop. They would do a better job fixing a computer than Best Buy and might also be able to sell you a refurbished machine at less cost than a new model if it comes to that.
I use a place like that, and they has saved my (work) life twice now.
um, “they have”