I've tried several different DELL original power supplies which I know work and which power/recharge other D610s, but they do not power mine at all. The BIOS reports "AC adapter type: none" at all times.

I noticed that there are no connections for a second drive on this system yet there is a bay for a 2nd drive. Is there a kit to be able to add a 2nd drive?

As I began using the newly bought PC, I noticed that my screen was blinking randomly among the day as I work, sitting in front of this PC all day/everyday 8 AM - 5PM. Sometimes 3-4 times in 5 mins or sometimes no blinking for 3-4 hour.