"Flashing Cursor" Lockup on Studio 1558

I am seeking some other opinions on how to deal with a problematic laptop.

First the issue: The new laptop has completely failed twice with the same issue: a "flashing cursor" and a black screen on powering up. Long story short: on power-up, I can hit the "F-12" and run dell diagnostics — all hardware tests pass; however, the booting sequence never gets to the Windows 7 OS — the laptop freezes with the flashing cursor. The first time it happened, the system was successfully restored to the factory defaults by booting from two Dell Datasafe disks that I created when the laptop arrived.  However, within 48 hours the same issue re-occurred. On the second occasion, the Dell technical phone support had two options:
1) Exchange the laptop — new one to arrive in 20 business days;
2) Install refurbished motherboard & memory in the laptop via a tech service call
I felt that my only real option was option 2). However, this replacement is being done without really knowing the cause of the issue — all hardware diagnostic tests and checks have passed without giving any clue as to the root cause of the problem.

My two concerns:
1) the issue will re-appear after the installation of the refurbished parts but my 30 day exchange period will have expired in the interim.
2) this laptop is for my daughter who is leaving town for school — 20 business days will be too late an arrival for a replacement before she leaves.

My questions:
1) Is there a method to expedite the exchange of a laptop faster than 20 business days?
2) Does anyone know what the root cause of this issue might be?
3) When, exactly, does the 30 day exhange countdown start? Order date? Shipping date? Date Received?

Thanks in advance,

Clayton