I recently bought some ICOM IC-F420S-10 and IC-F420NW-10 UHF radios at
a bankruptsy auction. They had been used on the forklifts of a large
factory. Each radio has the original ICOM HM-100N mic and a small
magnetic base roof mount antenna.

The radios all appear to power up fine. When connected to a 12V supply
and the power switch pushed, all the buttons are backlit, the indicator
light for whichever frequency is selected lights and every time the
freq increase/decrease or volume buttons are pushed the radio beeps.
Also, when the mic is keyed the TX/RX button and the frequency 1
through 5 indicator lights illuminate.

The problem is I can't receive anything on any of them. Complete
silence.

I'm not a radio operator; I'm just trying to check these out to see if
they work before I resell them. The literature I downloaded online
said these are PC Programmable and password protected. Is there a way
to make these xmit and receive without a password? How do you input
the password?

I downloaded an IC-F320/F420 manual from ICOM but the manual shows a
slightly different model......one that has alphanumerics and other
symbols on the function display instead of just Channel 1-4 lights and
TX/RX like mine.