Ugh!!
Yeha, ripping out a serial port sucks. But, that may be a replacable item if you have a serial port header and it was something that was bolted to the case chassis or else a slot mounted option. But if it was a serial port attached to the mainboard, you might have damaged more stuff than you think, so be extra cautious.
The good news is you're saying youre using a standard serial cable with a null modem adaptor. That says you're doing what the manual says to do.
If the SD3 came with software, you have two things you need to do:
1: Install the software, which clearly you have done. This should also take care of configuringthe serial port properly.
2: Ensure you're using the right serial port, either Com1 or Com2. If you have a regular modem laying around(one that attaches serially) or else some other device you would communicate with on a serial port, that should tell you which serial port to use. The software should give you a choice of which serial port to use.
3: Have you put the console in a mode to accept communication on the serial port? This is an easy to skip step if you're not familiar. It's documented in the manual.
After that, I really can't help because I don't have an SD3. I do have a few computers with serial ports, but I'm finding my newer ones(I build all but my laptops) lack them.
Again, some software wants a null modem driver, some don't, it just depends on the software. The manual is unclear as to the exact requirements, so I am assuming, perhaps WRONG, that you don't need a null modem driver. I find TCP/IP apps that use SLIP or PPP want a null modem driver to facilitate that bridge for networking, that's been my experience.
Test your cable. Test your null modem adaptor. Is your cable a 9 pinF to 25 pinM? Is your null modem adaptor 25-pin to 25 pin M-F? Are you then using a 9 to 25-pin adaptor? I don't want to go into the endless permutations. If it was me I'd build my own cable as I hate adaptors for this sort of thing. but out in the field, I have my Cisco cables, my USR/3Com cables, Ascend cables and other speciaity cable sets, some may or may not include adpators.
I think you need a helping hand from an expert. Call Elation Support. Good folks there, they'll help you out right.
Don't quit. You'll get it.