"tool 1 failure ! temp limit reached shutdown or reboot "

hi
i have a ctc dual extruder with mightyboard , sailfish 7.6when i boot it, i have a message
"tool 1 failure ! temp limit reached shutdown or reboot "
i try to invert thermocouple, no change, i try to disconnect thermocouple, no change

last problem, when i plug on a pc with usb, plug and play is not working, and the printer is not detected by pc
so my problem is that the mightyboard is dead ?
or maybe just a chip ?any suggestion for fix it ?
a last question, maybe i can use this printer with only 1 extruder.... but how ignore the message ?
thanks for help