Hmm, mostlikely it seems a hardware error. Last thing came in my mind you may try to NVRAM_CLR via jumpers as below   NVRAM_CLR — Clears NVRAM. The NVRAM will be cleared when the jumper is closed (use the jumper from the password bridge). To properly clear, AC power must be applied (not necessarily turned on) to the system for about 10 seconds while the jumper is closed. Pins 1-2 shorted clears NVRAM PWRD_EN — Password enable. The system password will be cleared and disabled when the system is started with this jumper removed. Pins 1-2 shorted enables password          
Hello I have a Dell poweredge t300. I was trying to upgrade the memory from 4 gig to 16 gig. The RAM went in fine and told me me there was 16 gig I decided to put an extra 2 gig in it so power down and then immediately got an error message saying the CMOS battery was not working so so I put a new CMOS battery in booted it back up and it was given an E20 11 memory card error I've tried to put the old memory back in which have made no difference. Currently the t300 will not post is there anything else I can try to bring the machine back to life. Thanks
Poweredge t300 e2011