I was having problems booting to Apple Hardware Test and decided to reset the PRAM. Big mistake; now it won't boot at all. It's a Mac Mini 3,1 (Early 2009) running El Capitan. PRAM reset chimed twice. Now it chimes after power button hit but then just stays at a gray screen forever. Using a wired keyboard plugged directly to USB port.
I have tried everything I can think of: Reset PRAM again; SMC reset; Safe Mode (Shift key, pre-boot); Verbose mode (Cmd+V); tried to boot to install disk #2 (10.5 DVD, with utilities, currently loaded in drive) for Recovery mode using Cmd+R; replaced PRAM battery; AHT from disk (D key); Choose boot drive (Option key); reseated RAM chip in a different slot; unplugged everything overnight then tried again this morning.
All fail. Light comes on, I get dong chime, drive spins for a bit, but then just a gray screen. Any ideas? Thanks a lot. Kind of desperate here.
[I am aware I should probably buy a new Mac but I'd like to make this one work.]