Ignore me, because I am not an expert, and I am sure experts will chime in later.
I do not like the look of that saddle valve above your shut-off valve. That looks as though it is/was leaking.
And while your electrician was right to jumper your water heater (with the copper wire) the clamps he used do not appear to be copper or brass or bronze. If they are steel they will react with the copper pipe.
And I wonder if your dielectric union on the cold supply became faulty?
And where is that flue going? (unrelated to your problem). Is it allowed to do that someone? And it should be screwed to the vent hood.
Your pics should generate a lot of responses.