|(Oops - OtheHill's post was not there when I started typing this)|
Your Boot Device Prority list
was set wrong.
When you removed then re-installed the cmos battery, the bios set the Boot Proirity list to defaults that work for booting from a bootable disk in an optical drive.
What is it set to now?
I have no idea why the ! in front of CD-Rom - I've never seen that - perhaps that is to show you you can't boot from it?
You always have to re-set the time and date to other than defaults when you remove the cmos battery, or when you remove it then replace it, or when you clear the cmos by moving a jumper on the mboard, then moving it back, either in the bios, or in the operating system before you reboot the computer.
If you set the bios to defaults in Setup, only the current time and date settings are retained of the user settings that were not defaults.
In order to be able to boot from a bootable disk in an optical drive, the CD drive or similar has to be listed before (above in this case) the bootable hard drive. It doesn't necessarily have to be first in the list.
Anything you want to be able to boot before a bootable hard drive must be listed before it.
If the hard drive is listed before the optical drive and is bootable, or in any case, if the hard drive is bootable, the bios never attempts to boot anything else in the list listed after that, including other hard drives that may be in the list, or in a list elsewhere in the bios settings, if you have more than one hard drive.
E.g. the possible correct ways for your case
or on a computer you can connect a legacy floppy drive to
Sometimes floppy drive is listed even if you don't have one connected. That causes no problems - the bios never examines a floppy disk in a legacy drive to see if it's bootable, since the drive is not there.
I've found if a legacy floppy drive is listed after the optical drive, for most bioses, a bootable floppy in the floppy drive will not be recognized as bootable while booting.
For most if not all bioses, if the boot order is set up right to recognize a bootable floppy in a legacy drive, if the floppy in the drive is not bootable, the bios does not attempt to boot from anything else listed after it.
That may apply to a USB floppy drive as well, I don't know.
If your bios recognizes a bootable flash drive or USB connected external drive, I've found that with at least some bioses, if the boot order has Removable drives or similar first , if you plug in a non-bootable flash drive or USB connected external drive (or a USB floppy drive?), when the bios finds that is not bootable (or the floppy in the USB drive is not bootable?) , it does not attempt to boot the next thing in the list.
I have encountered one recent mboard that does that even when Removable drives or similar is not in the list, for a non-bootable flash drive.
Brand name systems often have Network Boot or similar listed in the bios boot order. If the computer is normally supposed to boot from a company or institutional network, that's usually listed first. The bios never attempts to boot from other things in the list if that's successful; if that's not successful, according to what I've heard of on this site, you get a network boot specific error message and the bios does not attempt to boot other devices in the list.
Many bioses will only boot from a bootable disk in one optical drive if you have more than one. In that case, insert the bootable disk in the other drive, or another drive if you have more than two, if a bootable disk is not recognized while booting.
OR, in that type of bios, when there is more than one optical drive, there is either
- a list of optical drives, often near the boot order list or similar - the optical drive you want to boot a bootable disk from must be listed first.
- or - less likely - there is more than one optical drive listed or available to be listed in the boot order or similar list - the optical drive you want to boot a bootable disk from must be listed first.
The network adapter has to have a boot rom chip or a similar capability on the adapter in order for you to be able to boot from a network. Most network adapters don't have that, but sometimes ones on brand name systems do, already, e.g. models marketed as for businesses. The rom chip must already have the data required on it to be able to boot from your network, or if the adapter has the capability, you can run a configuration program on the network adapter during booting to set settings right if the defaults are wrong for your network.