Windows 7 64 bit activation probelm

I've had my Inspiron 3847 since 2014. I bought it with Windows 7. Everything has been fine for years.

Suddenly I'm receiving "counterfeit Windows" notices from Microsoft.

This immediately followed these two events:

1. I recently had to replace the hard drive.

2. Shortly thereafter, I was visiting the Dell support site and noticed that there were several levels of updates for my BIOS. I downloaded the latest, labelled "urgent," perhaps foolishly, since it's not like anything was malfunctioning.

One of these two changes presumably caused my Windows activation problems, almost certainly the second.

What the heck do I do?