Once it's verified as working, as always with these units, recommend popping the top and checking the battery and PSU caps. Maybe even power supply voltages. And be sure it's rated for 110/117/120 before plugging in. As wall voltage has increased over the years, tweaking the PSU rails may be needed.
If the battery is in a clip, someone has replaced it at some point as the originals were soldered in. If needed, a flush mount CR2032 battery clip from tayda, etc should work. Anything under 2.7ish means it's done.