Hi, I have an old iMac 17" intel (the white one). Worked well with bootcamp (Snow Leopard & Win XP) for a long time. Tried to change the partition sizes because I needed more at the windows side. Made an error there by changing the OSX partition size in disk manager instead of bootcamp assistant and after increasing the windows partition and installing windows ended up with a system reporting missing a windows file straight from booting.

From that moment onwards many features you expect from your Mac didn't work anymore like (keyboard boot commands to select boot device (Alt), ejecting CD etc. A windows CD was still in the drive.....Got completely stuck there.

Because data is saved elsewhere and software can be reinstalled, I decided to open the iMac and extract the CD manually and erase the HD to start from scratch.
After having done that (HDD reformatted via usb on other mac and CD removed from drive) reassembled the lot and booted..... Error message: no bootable device found....
Tried Snow Leopard DVD, nothing! Had to remove it manually again and as a last resort tried the Win XP installation disk....which worked and installed!!!

So installed Win XP knowing this wouldn't work properly but expecting it somehow to 'unlock' the strange behavior of the iMac. Result was I ended up with a windows installation, keyboard startup shortcuts still not work, (CD ejecting works only via Windows Explorer, not via mouse button or other OSX options).

Figured that somehow the Mac was holding knowledge of the fact the latest activity was installing windows and therefore showing this behavior.
Opened the system again, reformatted the HD again: Mac OS Extended (Journaled), removed the battery (resetting NVRAM & PRAM didn't work either by using boot+Command+Alt+P+R)
Short-circuited battery circuit to make sure nothing was left behind.
Reassembled the lot and......error message: "No bootable device -- insert boot disk and press any key".
So I know:
- HDD is OK (works and is visible on other iMac using via USB)
- CD/DVD drive is OK: I could install Win XP with it.
- Snow Leopard DVD is OK, tested it on other iMac
What it doesn't do:
- Boot from drive nor from Snow Leopard DVD
- Respond to keyboard commands at boot time (no CD eject which is very frustrating)
What I would like:
- Reset it completely and install OSX again.

Sorry for the lengthy post, but is there anyone who may have an idea how to proceed?

Thanks in advance!!