HD3 Handset dropping call, can't connect, now screen blank

I have been calling my mother daily via Ooma lately, ever since she was admitted to the hospital with pneumonia about 2 1/2 weeks ago (and has been home now for about 1/2 week). Yesterday, the call signal dropped about 20 minutes into the call, and I saw the onscreen messages “Scanning for Ooma base station”, then “Connecting”. I didn’t attempt calling back at that time, because it was already time for me to go to work. This morning, I attempted to call again (and at least a couple of this morning’s call attempts are showing up on my Ooma dashboard). The first couple of times, the HD3 handset would ring once, and then the signal would drop, and I’d get the same “Scanning for Ooma base station/connecting” messages, but at least the screen stayed lit. The last time, there was a slight delay before the first digit of the phone number I was keying in displayed, and then the screen went blank – and has stayed blank while plugged into its base to recharge. (My Ooma Telo Air is showing a blue light all this time, too.) What is going on with my HD 3 handset? Do I need to replace it? Or is there some way to fix these issues with the blank screen, failing to connect, and dropped calls?

Looks like it was a battery issue. I checked the battery compartment, and apparently we had installed alkaline batteries (not rechargeable batteries, per the instructions in the HD3 manual) when we first set up our Ooma just over a year ago, and the recent frequent calls to Mom caused the batteries to drain. I put new batteries in just now (more alkalines, but I promise I’ll buy rechargeables this week), and the HD3’s screen is back to normal.