Clicking noise, will not start, humming sound from dash

Hi,

Yes the clicking is the solenoid. This means there isn't enough power to hold the solenoid closed. Causes are:

Bad or dead battery.
Bad battery cables or cable connections.

Given your gauges are bouncing around it may be a bad ground.

I would suggest ohms checking:
both cables to the battery terminals.
Both cables from the cable end to the cable at all 4 ends.
The positive to the starter terminal.
The negative to the engine block and to the body.

You should have 0.00 ohms at each place, anything higher is a bad connection.

Here is a guide to help you:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Let me know what you find.

Rich