How do I disable a firewire port on a MacBook Pro?

i have a macbook pro circa 2011-ish(?) it was the last model made with a firewire port. i work and hobby in film, and one of my older cameras connects via firewire. i also have a very old and very used, yet reliable 1TB WD external hard drive that connects via firewire. about 6 months ago, while connecting the camera, there was a spark as i plugged in the firewire cable. i immediately disconnected it and powered down the mac. after restarting, the camera no longer could connect to the mac. as an experiment, to see if the issue was the camera or the mac, i dug out my old WD hard drive and connected it to the same firewire port using the same cable. the hard drive has its own power source and an additional USB connection. so i plugged it in and connected it via USB first and it worked fine, then i tried connecting it with firewire, but nothing. but oddly, the firewire port was supplying it with power (electricity). i unplugged the HD's power cord but left the HD connected to the mac by the fire wire and the disc stayed spinning and lit up, but still didn't show up on my desk top or disc utility. i then ran - diskutil list - in terminal and the unpowered HD showed up on the list. i then disconnected it from my mac but immediately certain features stopped working on my mac. also strange files (especially folder names and icon pics) that had been erased off that hard drive years ago began appearing randomly on my mac. the next time i turned on my mac, it loaded 3/4 of the way and got stuck, so on a lark i plugged in the unpowered HD to the firewire port and the computer immediately finished loading. shortly thereafter the same happened when my mac went to sleep, it only woke if i plugged in that particular HD without its power cord to the firewire. everything else worked fine on the mac. but for whatever reason, the firewire port began "searching" for the HD when it was not plugged in. the fans would blast and the cpu would go through the roof. the problem just keeps getting worse. the screen freezes often, and i need to plug the HD into the firewire port to unfreeze, but if it freezes again or a program won't open or my keyboard becomes disabled, i need to unplug firewire from the HD and plug it back in and everything works fine... for a bit. the last few days the problem has become much worse. the mac seems to be constantly checking the firewire port, i'm assuming for its functionality, but when it sees its been fried, i assume it wants to see a complete circuit or whathaveyou, it just goes berserk, making a loud clicking sound and spinning the fans and discs. putting the computer to sleep is the only way to stop it. i've done clean installs. SMC and PRAM resets. but nothing works. depending on what i'm working on, i run snow leopard, el captain or sierra. the results are the same on all three operating systems.

i'm afraid unless i can permanently disable the firewire, my computer is doomed. i tried removing firewire's kext files to no avail.

anyone out there have a solution?

i could really use one!

thank you so much.

the hunters dog