Since you've already been on Linkedin Sales for a while, and know the landscape, a good first step could be to try to further optimize the efficacy of that outreach (unless it's already extremely effective). Anything learned there should be translatable to other channels as well. I can't give advice on that kind of optimization without seeing what you're already doing.

In terms of other channels:

1) you can look on job posting websites for any companies looking to hire someone to do what your IT solution does. For instance, Angellist, etc. Reach out to them with a solution that is presented as obviously cost saving and efficient relative to having to hire someone to do it.

2) if your product could work for small companies, maybe pair up with a local 'startup accelerator' and offer your services free for some time (e.g. 1 week?) to all of their participants.

3) look on relevant online forums for people asking for help with the problems your product solves

etc.

Let me know if you'd like to discuss your product and potential outreach options and optimizations in more detail,

best,

Lee