mine doesnt have wires just a silver terminal top and bottom of the battery.
the top one (as you look from the back as you expose it) is actually "riveted" permanently looks like its welded but it isnt? might be? . when i say top i actually mean top when looking from where you are excavating.
from the display jbot you are right its bottom.
this took great care to get off the battery. but i did it.
both terminals were intact after my "excavation" and a new battery lit uip the display with dashes and degree C
@marc friedman i got the unit off a pal and he refused to give me the sensor (im guessing due to my sexual preferences.)
the thermistor ive bought reads correctly re hotter temp display goes up and cooler works too.
ive just got to work out what resistor to solder in somewhere.
if i had the original sensor or one with the same spec i would be good to go.
i will post my findings when i get it working properly.
i can imagine i will get it reading say 10 degrees warmer or colder and settle for that..