Of course you can send a picture (attach to this email but please answer questions on my website so others can benefit), but I think I know how that looks, I’ve seen those melting collars many times on my inspections. Take a picture or a few of your installation: vent pipe connections if attached to another vent connector (e.g. from a furnace), chimney connection (take a couple of pictures from several feet and a close-up).
Also list the BTU’s of your water heater, draft hood diameter output (the one that came with the appliance), b-vent diameter, chimney flue diameter (if possible), list of other appliances connected to the same chimney (if you have a furnace, get BTU’s from the manufacturer’s tag, describe type: natural draft, motor induced draft…), chimney type (brick, metal, inside the house, exterior wall, approximate height, etc.)
One more thing, are there any appliances, fans, fireplaces in your home that can create negative draft. For example, an open damper in your fireplace could do that and compromise water heater’s draft.