Sorry to hear nothing worked.  I presume you have reseated all the cards
and DIMMs in case they have been moved during the surgery.

Is the BIOS PROM removeable ?  If so, can you copy the BIOS to a new
PROM ?  This is rather involved as you need a matching flash RAM and a
suitable burner.  I have never seen a PROM fail but 'updating ESCD' does
write to part of it and I suppose it chip will fail sooner or later.  Or
(assuming the chip is in a socket) can you find a matching motherboard
and try swapping the chips.

Hopefully someone else will provide some easier and more helpful
suggestions.

What procedure you used to reset bios data? I hope you wrote down original
configuratin, before this reset made. Setting BIOS correctly to be used by
NT server could be sometimes a bit tricky. But you hangs even before BIOS
try to load anything, so first you need to solve this problem.

Get out this new NIC. Then try to look for help in your motheboard (BIOS)
manual. I think resetting of ESCD table could help here, as updating is
evidently messed up. Try to find ESCD reset option on PnP setting or Boot
settings BIOS setup page (unfortunately, this option is now obsolete, but if
you have older machine, you may have luck having it still here). Setting
this option to ON and restarting machine usually works like charm in your
situation (this option will apply just once on next TURN ON and set itself
to OFF automatically during procedure) . If this not help, you should to
remove all adapters except video. Try to disable all unneccessary onboard
devices. All you need is video and keyboard.  Try to reset ESCD table again
and if you go over, continue by adding devices back one by one.

Seems your new NIC card inflicted rearrange of ESCD table by BIOS PnP
manager and that this caused two incompatible devices to try to share one
IRQ. It may happen even with PnP devices. Number of hardware interrupts in
standard PC is very limited. So new devices are made to be able to share it
with other "compatible" device. PnP devices present itself to PnP manager
with tag, containing also information about possibility to share IRQs.
Unfortunately, some devices are not able to cooperate even they present
itself as able to share IRQ. For example if you have 2 NICs from 3COM, they
both will share the same IRQ and there will be no problem. But if PnP
manager set 3COM NIC to be shared with Creative Soundcard, you can have
problems like you described in your post. It is sometimes possible to
rearrange devices, but you will sure meet another problem - Windows NT do
not like devices to be rearranged. Resetting of CMOS settings on NT server
machine is really dangerous, because servers usually have a lot of disk and
network devices that needs special BIOS settings to be functional under NT
system. If you know not original settings, you can spend hours trying to
find them again.