January 4, 2024

a) I subscribe to your analysis and to your plans.

b) Please remember that I composed my previous letters to you on the basis of only fragmentary history, a limitation which unavoidably impairs the diagnosis.

c) If you find:
c1) with the electricity disconnected, that the upper heating element has a resistance, nominally 18.75 Ohms and
c2) with the electricity connected, there is 240V Voltage between the upper terminals 1 and 3, then 
c3) the very likely cause for failure of water to heat is (possibly intermittent)
c3.1) failure of the red button reset circuit breaker
c3.2) and/or failure of the upper thermostat which is combined in
the same module with the red button circuit breaker.

You can purchase replacements for "everything" in a kit:
https://www.amazon.com/EWH-03-Electric-Tune-Up-Thermostat-Elements/dp/B09NM25QK5/ref=sr_1_3?keywords=water%2Bheater%2Brepair%2Bkit&qid=1704419234&sr=8-3&th=1

or from Home Depot:
https://www.homedepot.com/p/Everbilt-Electric-Water-Heater-Tune-Up-Kit-EB20018/204834414
where the required wrench would need separate purchase:
https://www.homedepot.com/p/Everbilt-5-in-Element-Wrench-15016/205680998

Any unopened kit you could return to amazon.com or Home Depot.

The $45 or $50 spent might save you a special trip.