I have a hernia but my herniated junk is better {more painful} than HP junk.
HP was once the two letter symbol of quality, I still have an HP 12C Financial calculator that I bought in 1982 or there about, which still works perfectly.
I haven't changed batteries for 5 years and I use it several times a week.
Any old timer that ever understood present value, future value, lease rates, leveraged leases, and how to make money because you knew more about fractional rates of return than the guy you were dealing with, knows that the HP 12 C was/is a great piece of electronic help.
The individual still needs to know what to do with the financial information.
I've met so many "financial advisers" that don't know their ass from a sink hole, that when I watch the TV commercials about, annuities, gold, guaranteed investments...etc. I want to either puke or sh*)t.
When HP was was in the 'quality business' they were great, after the dumb bitch took over, they went straight to mediocre hell, in a 'profit today' hand-basket.
Unplug it. Plug it back in. If that doesn’t work, but a new one. That’s high tech in 2020.
Most likely a problem on the other end, sounds like to me.
Purchase a new one from a store that has a 2 week or more no-questions return policy.
It could be the line...likely it’s the HP.
Have you tried turning it off and then back on again?
Sorry. I couldn’t help myself.