I pulled an old LC III from 10+ years of storage with the idea of getting rid of it. I have little experience with Macs, but it booted just fine and I could see it was System 7.1, and had a bunch of installed SW on the HD including MS Word, Norton Utils, etc. A week later it would not boot, and just gave the flashing "?" after trying to spin up the HD twice. I read about dead battery problems and yes it was dead so I replaced it. I also did the option-alt-P-R reset thingie to clear the old settings. I assume I did this correctly since it causes a complete reboot cycle.
The system still wouldn't boot the OS, so I created a boot floppy on my PC using softMac and the 7.5 NAD image. That does boot up, so I guess the RAM is OK, but the HD is still not recognized. I see no menu options to tweak settings related to bios/HD. This machine has no Ethernet or other network access. I have disconnected and reconnected the cables, and reseated the two MB PROMs near the HD connector.
If this were a PC, I'd go into the Bios, check the drive settings and try a few repair utilities before I wrote off this disk as a lost cause. Do dead batteries cause you to lose disk contents? Is there a better boot disk image with some actual drive tools? Are there any voltages I can check? What to do next?