Dell Precision T7920 no boot after support assistant update

Hi People,

Could do with a little help but please be gentle as I'm not a computer person so keep the words small and imagine you’re talking to a dog or disinterested toddler!

I have a precision T7920 and a week or so ago decided to use the support assistant to do a full system scan.

After the various checks and angry spinning of fans it updated and then asked for the restart to which I kindly obliged and restarted the machine.

On the restart it did its usual gentle spin of the fans and then followed immediately with the ‘turn off click’ and then constantly repeats this cycle whilst the power button flashes/blinks amber.

The power button only blinks amber and is a constant flash/blink with no white flashes/blinks.

The power supply shows a green light and when the power supply diagnostic button is pressed the fans spin up.

As I’m not a computer person I’ve consulted the all-knowing internet and have drawn a blank but in the process have found this forum and I am prepared to endure the ridicule & abuse in order to try and fix the ‘starty up, shutty down, amber blinking’ paper weight of a Precision T7920 workstation!

So in summary…..

• Does turn on.
• Then turns off immediately.
• Repeats the turn on and turn off cycle constantly thereafter.
• During the whole process the power button slow blinks/flashes amber.
• There is a green light present on the power supply during start up.
• The machine has been updated with the Dell support assistant several times since I obtained the refurbished unit in September 2022.

So, where to begin?............ 

Many thanks in anticipation.