Hi,
The flashing amber power light indicates either a faulty motherboard or, more likely, a faulty PSU. Modern PSU's dont always go with a bang anymore, they usually just quietly give it up.
On the back of your PC there are 4 status lights, A, B, C, D. These indicate component faliures like the memory or CMOS battery. Turn it on and see what lights you get and post back.
Be careful replacing Dell PSU's with generic ones, Dell have a habit of altering the pinout on the PSU connector. This results in either another blown PSU or a blown motherboard.
Good luck!
