Software has an emergency fire hazard shut down of the unit around 60C on the thermistors. Resistance falls with increased temperature, so a disconnected thermistor would read cold, besides a specific error msg for missing thermistor. So maybe there is a short circuit in the thermistor wiring, or a system board defect. You can measure the voltage on the thermistor yellow leads (one of which is system ground, the other through a 21K resistor to the 5v system logic power, so the cpu can read the divided voltage, around 1.5v I forget exactly, with 10K thermistor at 25C. The lithium replacements for NiMh synthesize the thermistor signal with a faux temperature rise simulating NiMh behavior at end of charging. I don't have specific Botvac
data, presumed similar XV. The XV thermistors are identified in the Lithium Power Revisited thread.
Thermistor readings by the cpu are available over USB with Neato Control Program or terminal emulator.