I can't hear anybody on the external speaker or the internal speaker

It's possible your ASQ is turned on. To check if it's turned on you will need to access the function menu.  To access the function menu press and hold the FUNC Button for approximately two seconds until the LCD meter displays FIN, then release the function button. Then press the FUNC button again to until you see ASQ. Turning the channel selector knob will allow to activate the ASQ or deactivate it. 

An easier way of turning it off is to perform a reset. 

If you’d like to reset perform a reset, please do the following. With the radio turned off, press and hold the FUNC, COLOR & SCAN buttons. While still pressing and holding them, power the radio on. The radio will display “REST ALL,” now release the buttons and wait for the radio to display “REST END”. Then turn the radio off and then back on, it’s now been restored to the factory software settings (ASQ is off).