That sounds like the battery is dead or one or more of your battery cables/ connections is bad.
You have to learn to test as if you are driving down the road.
Let's say your battery cable goes from battery post----to battery clamp---to cable----to starter relay---to battery.
Maybe it DOESN'T let's SAY it does.
You have a ROAD there. A ROAD MAP.
Measure by stabbing RIGHT INTO the tops of the two battery POSTS. What do you have? If it's much below 12, either the battery is discharged or defective. Charge it up
"Rig" a way to crank the engine either with remote starter button, or screwdriver to jumper the starter relay Another "rig" is to turn on headlights. Either of these will LOAD the battery to PULL IT DOWN and create CURRENT FLOW through the wiring which will show up weak spots
Back up to your road map. First make sure the GROUND CABLE is OK. Put your meter into a low voltage scale. CLIP one lead to the engine block. STAB the remaining probe into the top of the NEG battery post. Now jumper the starter relay. What do you read? Should be VERY low, maybe a few tenths of 1 volt. Anything over .2--.3 is of concern. If so, CLEAN the battery clamps and terminals and try again.
Now Let's start down the ROAD MAP we laid out earlier
Let's say your battery cable goes from battery post----to battery clamp---to cable----to starter relay---to battery.
For now, leave your meter clipped to some point on the engine block. Stab your probe into the top of the POS cable. jumper the starter and read the meter WHILE THE STARTER is cranking. If it is below 10V charge the battery. If the battery won't "come up" take it somewhere and test it. Maybe it's defective/ worn out/ old
Now, with that reading, proceed "down the road." Move the probe to the starter relay. "Let's say" you read 11.3V when stabbed into the top of the battery post, when cranking. "Let's say" you read 8V at the starter relay.
WHAT DOES THAT TELL US?
There is a HUGE voltage drop there. Start by cleaning the battery post and clamp, and re-measure. Backtrack with your probe. If the voltage is OK (near 11.5) at the battery clamp, but low at the starter relay, then the CABLE HAS corroded internally and is bad.
It is simple You simple chase the voltage readings "down the road" that is the wiring PATH
If fact I often call it "the path." "The path" the circuit follows.
