If jumpering the starter won't crank the engine, the problem is likely under the hood. Remove and clean the battery clamps. If no improvement, get your test light, meter
Hook the meter/ light to the engine block, and stab the probe directly into the top of the battery post.
Jumper the two connections at the starter. If you show any voltage above a few tenths of a volt, or get a glow from the light, that cable is bad, or you have a bad connection
Do the same, positive cable. Put your meter on the starter relay battery stud an the battery positive post. Jumper the starter. And reading above a couple of a tenths of a volt means bad cable/ bad connections.
Now do the starter. Use a clip lead to CARFULLY clip to the starter large stud. Hook that to the meter, and the other probe to battery positive. Jumper the starter. Again, more than .2V or so means bad cable, bad connections.
You can also check from the block to the starter relay battery stud. Jumper the starter. What does the meter drop to? Below 10V means bad cables, or connections, or the battery is bad or undercharged.
