Hi,
I have same troubles on my DL360g7. After some voodoo dance, problem takes a solution by resetting boot volume value in HP SA storage controller configuration menu:
Enter SA configuration during server boot (press F8 when SA controller initialization finished)
in main menu select "select boot volume" option. Then press F7 for clearing boot LUN.
Save changes, and try to install EXSi again.
Hope it will make you a bit of happy
--
Grig