Mechanical Engine Damage Diagnosis

When diagnosing a no-crank or no-start situation, if the battery didn't show any problems, its better first to check for a mechanical engine problem(since cranking an engine with mechanical problem may worsen the case). lets go through the diagnosing steps:

Rotate Crankshaft By Hand: Try to rotate the crankshaft by hand two full rotations, if it rotated for two full rotations proceed to starter circuit diagnosis , else got to point 2.
Rotating a crankshaft is not an easy process especially on a V8 engine
Hydrostatically locked engine: This occurs when a fluid has found its way to a cylinder in the compression phase ( through intake i.e while crossing a lake, or through a leaky head gasket), which will prevent the piston to move up, which will prevent the engine to complete its cycle, which will cause the engine to get hydrostatically locked. To Check and fix that: remove the spark plugs on all cylinders and crank it (30 seconds at most), if the engine cranked and started splashing fluid out of the sparkplug holes , you have successfully detected and fixed the problem , else proceed to next step .
water is trapped between the valves and the piston , causing the engine to get locked

Faulty Belt-Driven Accessory: Belt-driven accessories (AC compressor, alternator... etc) could hold down the engine, to check if they are causing the problem, remove the accessories belt and try to crank the engine, if that didn't work proceed to next step.
A Faulty alternator could lock the engine up
Loose Or Broken Timing Belt: In interference engines when the timing belt breaks or slips causing incorrect timing, the valves will collide with the pistons binding the valves or luckily just locking the engine, remove the timing belt cover and check for lost belt teeth or a loose belt.
Internal Engine Damage: If all above didn't work its an internal engine damage.