Sorry about your situation. Actually, the interference may be the most complicated problem. It may come from a variety of sources, such as the battery, the motors, the ESC, the VTx, the PDB, etc.
1. Please don't power the camera directly by LiPo battery which can produce a lot of noises. We recommend you use FC 5V(1-3A)/PDB 5V(1-3A)/BEC 5V(1-3A) as the input source.
2. Please make sure the GND on VTx and Split is corrected connected:3. Solder a 220~330uF electrolytic capacitor between the battery soldering pads. And also solder 10~22uF tantalum capacitor between the power input soldering pads
4. Change to another VTx. Some VTxs can create strong noises.
5. Change to another name brand PDB. Some PDBs cannot supply clean power output.
6. Add an insulating mat between the mount of the Split Mini and the frame
Please check the link for reference: https://www.rcgroups.com/forums/showpost.php?p=38034969&postcount=543.You may also insulate the antenna which is conductive form the frame.