I feel terrible about the pain you have suffered and only wish I could ease that pain.
As far as what seems to help me establish contact:
1. Run white noise. Any soft contant sound like a fan. There are white noise machines you can buy with a variety of sounds, like waterfall, rain on the roof, babbling brook, bird sounds, etc.
2. If you have ashes, keep them nearby.
3. Talk to him every night, even if it is just saying hello.
