Pre-BIOS failure

If the power switch light is off it means the system isn't receiving power.  Try reseating the power cord on the back of the machine and all the cables coming from the power supply on the inside of the system after unplugging it from the wall.

 

If the power switch is a steady amber color then open up the system with the machine unplugged from the wall and go through and reseat all the hardware and cables inside.  This would include the processor, memory, graphics card and all the other expansion cards.

 

It's possible that during shipping some cable or device worked itself loose and is no longer making good electrical contact.  If the above mentioned items do not cure the problem then contact Dell Tech Support.  If they are unable to correct the problem then keep in mind you have 30 days to return the system with no questions asked.  

The only other suggestion at this point it strip the machine down to the bare minimum to see if it will at least boot up.  By bare minimum I mean disconnect all cables from the rear of the system except for the power cord. Then go inside and disconnect the cabling to all the drives and remove all expansion cards.  What you want left is just the processor, memory and graphics card.  If she boots then start adding one thing at a time until the no boot scenario returns.  That should give an indication what device has failed and is preventing the boot up.   If the machine still fails to boot then call Dell.