You should look into rapid Transcranial Magnetic Stimulation (rTMS).General anesthesia is not required, and the magnetic field can send an electrical impulse to a specific part of the brain.
You have a faster recovery time, and short-term memory doesn’t seem to be affected as much as ECT.
I know someone else who had treatment resistant severe depression, and it worked for them. I just recommend exhausting all other treatments before trying it.