Land Rover Repair: ground points, land rover discovery, radio chassis

Question
How do I measure resistance from chassis to ground?  As for the fuses, yes we did check them and I have the radio code but the radio will not power up.. no lights or nothing, just total dead.  It probably is fried.  

THANKS SO MUCH FOR YOUR SPEEDY REPLY AND HELPFULNESS!
-------------------------

Followup To

Question -
I have a 98 Land Rover Discovery series I.  We have just replaced the alternator and now the radio will not power on.  The fuses all appear fine. I think this may be a grounding problem.  Where are the gound points that I should check and what do you think?

Answer -
You know the radio needs a security code, right?

And you checked your fuses, right?

If it's not a code problem I'd guess you fried it with an electrical transient while swappin galternators.  That does happen.  Check the power wires going into it and measur eresistance from the chassis to ground on the vehicle

Answer
With the car off, take an ohm meter and measure from the chassis of the vehicle (bare metal) to the radio chassis.  Reading should be near zero.  Cross the probes and note the reading, 0.4 for example. Chassis to radio should them be 0.6 or 0.7.  No more.