HP15C On Button won't respond

[jeffjensen04]

My older HP15C, circa 1986, has been super reliable. Today it shut off and would not turn on. I replaced the batteries and still no response. I removed the batteries and shorted out the terminals. When I replaced the batteries I received a PR ERROR code. Nothing would remove it except the F button.

Now the ON button won't turn it on, I have to press ON and then F back and forth several times and it turns on. Once it is ON, only the F and G buttons work. I do get a response from the SQ RT and Y^x buttons, but they give a series a strange numbers. It turns off when I press ON but will not turn bback on uness I repeat the ON -> F pattern.

I tried all the reset options I could find. Hold the minus key and then ON and release, hold the decimal key and ON and release, hold the multiplication key and ON and release. None of those options has an affect.

I removed the cover and made sure it was not corroded or dirty, it looks very lean.

Is it dead? Did I lose my best friend?