Make sure power cord is in good condition. At the end that goes into the battery slot in the camera, there is a 90° bend that can fray and short out.
Check the surge suppressor- if it gets switched off, none of the equipment will work.
Verify that the door to the battery compartment is shut all the way.
If left on, but unused, the camera will 'sleep'. Pressing the shutter part way will wake it.
Issues with the lens
the Lens should be fully locked into place. An unlocked lens won't work, and is at risk for falling on the floor.
a polarizing filter is normally on the 100mm lens. This will lead to less light getting in, so adjust shutter speed (or unscrew the filter and put it in it's case)
When using Helicon Remote, the distance scale (A) must be set at 0.31m-infinity, and the focus mode (B) must be set to MF (manual focus).