Mamba max beeps once every 20 seconds

My mamba max beeps once every 20 seconds and green and red leds light simultanously.
It didn't happen before.
I have not used it for a while and I am not sure what I have done to the esc.
It seems that it start to act like this after my firmware(1.17) update .
I have recalibrated the esc after the update.
Do you know what is going on about this ?