Well… it depends. This can be easy if you know the steps for preventing a shock from 220 volts, preventing the tank from collapse as you drain it, etc.
It can also be one of those weekend nightmares without hot water. The element seat or threads can be corroded in the tank so a new element won’t go in without a leak. The tank could be on its last legs. When was the relief valve checked?… they do fail when checked sometimes. There are so many ifs.
I prefer having an experienced plumber arrive with fast access to the right parts and a new water heater in the wings.
I replaced the heating element and reattached a wire that had burn off, the connection was all rusted must have had small leak for quite some time. I now have heat but I believe the relief valve is not working, how do you check it. I flipped it with my finger several times and nothing happens. The floor is still damp so I believe there is still a small leak. Thanks! jfn