Yup. That's my lesson. Or avoid lenovo altogether and go with a company that respects Linux, like old lenovo used to.
On my one the wifi is just blacklisted. Might as well remove it. I use a tp-link tiny usb dongle. It's a pain to have it always connected but I can live with it. Definitely not acceptable for what I paid for the laptop though.... not even counting the headaches with the battery.
But... you borrowed someone's computer and installed arch? I imagine they were never expecting to get it back...