You must have a USB keyboard and with many units where you plug in the keyboard can make a difference for initial detection.  Looking at the rear of the PC there are two USB ports with three more below those.  The two ports, side by side, is usually where the keyboard and mouse are plugged into.  If you are not using these ports, try them and see if the BIOS detects the keyboard. 

Many Dell's also have a recovery partition accessed by CTRL/F11 and if you can get a USB keyboard and get it working you can check to see if this system still has the recovery partition.  The recovery partition will restore it to the original factory image (and doesn't need any CD's for the install). 

(I'm an ex KC North resident - for 23 years).

Another trick is to unplug all external devices from the computer. unplug the computer and then press and hold the powerbutton for 10~20 secs. plug in only the keyboard, mouse, monitor. (Use the excellent suggestion by Fireberd as to where to plug in the keyboard and mouse) and then plug in the compter and power on.

I tried everything above but get a black screen saying:

Keyboard failure
Floppy diskette seek failure
Strike the key F1 to continue, F2 to run the setup utility

The next question, do you have a known good USB Keyboard?  Can you try that keyboard on another PC and see if it works?

Yes, the keyboard works fine on another computer

Looking at the Dell manual, if the Keyboard is good, it's likely a motherboard problem.   HERE  is the Dell manual.

Do you get any other failure indication?  Beeps? or  diagnostic lights?

Although you removed the CMOS battery, here is the Dell procedure to clear the CMOS.  Don't know if it's different from removing the battery.

Reset the current CMOS settings:

1. Locate the 3-pin CMOS jumper (RTCRST) on the system board..
2. Remove the jumper plug from pins 1 and 2.
3. Place the jumper plug on pins 2 and 3 and wait approximately five seconds.
4. Replace the jumper plug on pins 1 and 2.

I get two beeps and 1-2-3 diagnostic lights are lit up on the case.

I have reset the CMOS three times but continue to get the keyboard and floppy drive error

It says to hit the F1 or F2 but the keyboard will not respond

The USB mouse still works, why would it single out the keyboard?

Is it a matter of flashing the BIOS?

You are looking at a new motherboard. There are numerous post on this fourm with others with the same issue and the ones who these steps do not work for end up getting a new motherboard.

Is the motherboard even available anymore? I could not find it on Dell's site