spend a lot of my time GUESSING about cause and effect and my computers' behavior.
You go it!I used to write low-level code, including boot-loaders. That was a long time ago, but the fundamentals are still there. When there is a hardware failure you do not get a written report from a boot-loader. A low-level program gets locked in an endless loop waiting for the hardware to give a valid response. In modern PCs the fist loader is still very primitive and has low tolerance of a crude hard drive error.
The field test is to remove the drive completely and see what happens on the next power-up. That is so simple, there is little reason to make the first loader more sophisticated.
If you replace the bad drive with good drive that does not have an OS, you will get a meaningful error message from the first loader. Something like: "missing operating system" , which means the drive is physically readable, but does not have useful information for the loader.
Hard drives can fail at any time with no warning. Of course, the drive makers have tried to make drives that conform to user's expectations, But there exists four options in a competitive market:
1. Make it the low-cost wonder.
2. Make it extra large.
3. Give it high performance and long life.
4. Let it be so user friendly.
Some drive makers can hit three out of four, never more.
