Thermistor changed but still indicates -17º

CR Series Creality CR-10 Series
1

Hi, I have a CR-10 V3, the thermistor is broken, I have changed it, but it still indicates -17º, if I try to heat the extruder a message pops up indicating that I have to reset, the only way I see to reset is to turn off, I have tried another thermistor and it indicates the same -17º, does anyone have any idea how to fix it? thanks.

Message on printer:
Err: MINTEMP
PRINTER HALTED
Please reset

2

A friend more experienced than me has been looking at the printer, we downloaded the driver and the firmware file, but there is no way to connect to the printer, we tested it with 4 usb cables on all the usb connections of the computer, it does not detect it, so we cannot install the new firmware.