My primary laptop has a problem. The power adapter stopped charging the battery. And it also doesn't power the computer.

I did extensive troubleshooting to rule out the adapter (it works with my backup laptop, and the backup's adapter also doesn't work in the primary laptop.)

The charging port's power connection to the motherboard is fine. However, I haven't verified if the signal connection is making good contact -- the BIOS itself suddenly stopped recognizing the adapter, so it's possible that the center pin isn't getting through.

One computer store claims to charge $29 to diagnose a problem, but they didn't pick up the phone. Staples would charge $169.

I decided to order an alternate, USB-C adapter, which the laptop also accepts. I'm guessing it will work.

If not, it's possible the battery is loading down the adapter voltage. If that's the case, I'd buy a new (reconditioned) computer for merely twice the diagnostic fee. I'd get a model that takes the same battery, then swap the batteries to see if either adapter will work with the new battery. If this still leads nowhere, then I'll just use the new computer.