@GarageMonster
You say "F2" -- typo?
Should be F12, also to get access to device configuration or on-board self tests.
If those like Dell´s ePSA are available on your T7500.
New motherboard plus new RAM... Seeing the 1100W PSU´s wire harness, I break out in sweat.
Maybe better test the integrity of the new memory moduls on one of your other workstations first and install/update the new mobo´s BIOS with the old memory moduls installed.
Don´t give up yet.
You may end up as the personalized merger of intellectual and raw physical strength.
Get well soon & regards.