@Ben1029​ I have the same problem a ps2 keyboard didn't help. I get to the dell logo then get the msg keyboard not recognized.

never mind Ubuntu for now. You said you have tried every troubleshooting step for no POST.  not sure what steps you took.  No POST and no boot are two different issues.

If no video at all or you get stuck on Dell logo, that is no POST.  I would then remove all hdd, usb devices and keyboards/mouse, leave only one ram stick in DIMM1, and test if motherboard can POST.  If you see Intel boot agent after Dell logo vanishes, motherboard has passed POST but bios is set incorrectly to boot from network, hence no boot and you are stuck w the agent.  that is why you tried to enter BIOS but your keyboard is malfunctioning. I would try a very basic keyboard and try all available USB ports and PS/2 on the optiplex. You could have a faulty keyboard or USB port, but it is unlikely you have two bad keyboards at same time and all ports are bad.

I am able to get past the Dell logo to Intel boot agent. I have tried disconnecting everything besides the essentials for POST and tried 1 RAM stick in DIMM1.

My keyboard works on my other system just not on the Optiplex. I am unable to fix the boot order in the BIOS to not boot from network because my keyboard will not function during boot. It worked previously on the system and I have tried every USB port and PS/2 port(with my adapter) on the Optiplex. 

I do not have access to another keyboard

I have a pic of 9010 jumper .  9020 is probably similar.  move blue jumper from PSWD to RTCRST, wait 1 min, move back.

in the other user experience replacing w new battery was the fix.
the model of the battery is CR2032.  sold at many retail stores.  best deal I know is

https://www.bedbathandbeyond.com/store/product/everlasting-candles-replacement-cr2032-3v-batteries-set-of-5/1016888850

You said you tried resetting the CMOS/BIOS.  How did you do it?  I would remove CMOs battery, wait 1-5 min or overnight, replace w new coin button battery, and reset CMOs jumper on motherboard.  new battery is $2.  recently another user had a lot of trouble and new battery was the reported fix.
you system has passed POST, but for some reason it is not able to work w the only keyboard you have.  Do you have a laptop?  If yes try connect the usb keyboard to it and verify keyboard still works to enter laptop bios.

I took out the CMOS battery, unplugged the power chord and held the power button down for at least 10 seconds for a hard reset. 

How do you reset the CMOS jumper and where can I buy a new battery/what model? 

The keyboard works on both my laptop and on a different desktop PC to access BIOS.

On a side note, the keyboard has 2 USB inputs. One for RGB and one for actual key usage. I have tried using just the keyboard input and both(RGB and keys). Not sure if that makes a difference.  

I was able to reset the jumper, the computer booted to no time-of-day set please run setup. My keyboard is still not responsive and pressing F2 still does not bring up setup. I tried USB and PS/2 to USB. 

I will order the battery replacements. Is there anything else I can try? 

@Ben1029 Someone also had this issue of no keyboard response during boot.  He was able to fix it by taking out the battery to reset bios.  so if you could remove your battery overnight and reinsert it (or a new battery) next day, see if that helps.  That person also reported usb keyboard did not work in either usb port or ps/2 port via usb-ps/2 adapter.  once pc booted into Windows, his usb keyboard worked.  The problem is “some bios disabled USB connections to speed boot along; the common way to fix this is to use a PS/2 keyboard.”  You said you have no access to another keyboard. are you certain there is no old ps/2 keyboard you can borrow from someone?  (I have a few old ones) Perhaps a real old fashioned ps/2 kb is the only one that works.  The bios like a dog is not totally unresponsive. You just need to speak ps/2.

If you succeed to get in the BIOS, you want to look for option in there that says 'USB legacy devices', make sure it is enabled.
Save the settings in the BIOS, and exit.

I replaced the CMOS battery with a brand new one and that did not change anything. It boots straight to intel boot agent and continues to hang. Doesn't even say the time-of-day is not set, does this have something to do with the PSWD and RTCRST jumpers?

I will ask around but I no one I know seems to have an old PS/2 keyboard. Where is the cheapest place I can buy one? Or even just borrow it for a day