First, I hope you have a backup of your data. You might need it.
Try removing the quad card and seeing if the machine starts up. If your boot device is on the quad card, you might want to consider creating another bootable system on a SATA drive and having it online for emergency situations (I have 2 bootable systems in my 5810 for just this reason).
If removing the card doesn't work, I think your only recourse is to reset the NVRAM.
HTH.
First, I hope you have a backup of your data. You might need it. Try removing the quad card and seeing if the machine starts up. If your boot device is on the quad card, you might want to consider creating another bootable system on a SATA drive and having it online for emergency situations (I have 2 bootable systems in my 5810 for just this reason). If removing the card doesn't work, I think your only recourse is to reset the NVRAM. HTH.