Dell Inspiron keyboard issue

My Dell Inspiron is acting up. Since I removed some programs including MS Office the system boots to a diagnostic testing sequence, and the keyboard doesn't function. However, when I use a USB keyboard to get past the first round of testing it boots to another diagnostic set, and this one allows a choice for troubleshooting from a symptom tree. When I choose to test the keyboard it fails, and the error states that it is constantly scanning like a key is stuck. I checked all keys to no avail, and I ordered a replacement. When I installed the new keyboard I have the same problem. How do I correct a stuck key error when there is none?