keyboard issues with toshiba satellite laptop.?

I bought the l;aptop new in Jan. 2015. Its a cheap toshiba satellite, windows 8. It let us update to windows 10. In January 2016 it did an update that screwed the keyboard up. Many random keys type the completely wrong characters, or multiple wrong characters at a time. Over time I just used an external keyboard, and I noticed that the built in keyboard started changing the wrong keys it would type. I finally reset it to factory settings to see if that would work. It did not. The wrong keys it typed returned to how it was right after the update that screwed it up. Does anyone know where the problem may be?