Volvo Repair: 850 Does not start, starter solenoid, battery checker

Question
My 95' 850 will not turnover. All dash light come on, the battery appears to be OK (tested it with voltage meter), but I can't get the engine to turn at all. I do have what I think is a louder than usual "hum" coming from the solenoid? or starter relay? (it sits on top of the engine near the front with a plastic coweling over it.) I can't even jump this car. I don't appear to get spark when I attach the ground side of the jumper cable. Maybe incorrectly, but this leads me to believe there may be a problem with the battery groung wire - easy enough to clean and check. I had to push it (manual) and pop the clutch to get it running.  

Answer
Batteries cannot be tested with voltmeter, need to have battery checker that can put a load on it, to verify it will sustain voltage under load.
Also do not look for spark while jump-starting, not good sign and dangerous.
Check for voltage at starter solenoid while cranking. If there is, possible bad starter. If there isn't trace to clutch switch or rest of harness.