I think there's some confusion here... If a washer has dumbed-down temps, a heater won't make those temperatures any higher. What a heater may do, is offer the option of a sanitary or extra-hot temperature, great for cleaning but not safe for all items. And it may help by heating the water if the machine wants to do a hot wash, but fills with cool water because of a long hot water lag (long pipe run between domestic water heater and washing machine). Another thing: In most cases, dumbed-down temperatures are not forced on the manufacturers. They choose them in order to qualify for direct-to-manufacturer tax credits, as much as $250/unit. You could say that the manufacturers are selling out their customers to get the tax credits. The exception is traditional deep-fill agitator top-loaders. They use so much water that they may actually bump up against the mandatory Federal regulations. Even there, it's interesting to realize that, prior to 2011, there were no mandatory restrictions on water usage. There were energy restrictions, which may have mandated cooler wash temperatures on deep-fill machines (because all that water takes a lot of energy to heat). But there were no restrictions on unheated water, therefore no limits on how much rinse water could be used.

There is no control board on this machine. The timer is mechanical. Once the machine fills to the selected water level, it won't fill any further (except to a higher level) until the water is drained. Sounds like you've tried more than once to run a cycle ... did you drain the water somehow (lay the drain hose down to the ground, perhaps?), or is it filled and you've just tried changing the timer to various cycles? If the motor will not run in any timer position, at any speed setting ... suspect the motor capacitor, motor start switch, speed selector switch, or timer. Or the lid switch, but that typically affects only drain/spin ... it should agitate with the lid open, except if it's a new enough model with a revised lid switch design that also prevents agitation. The motor is accessed by removing the entire outer cabinet ... NOT from beneath or the back. You can find video clips on YouTube showing how to disassemble the machine.

It did fill now, but now on the last cycle. Did you mean "not on the last cycle?" ... meaning the 2nd load didn't fill to a reasonable level for the wash period? Washing large comforters on GWL11, use the Delicate cycle, manually set High water level. A broken agitator fin prevents proper sensing for the auto water level function. Resistance of the load against the fins during a series of test agitation strokes is part of the sensing process. Broken fins also contribute to off-balance incidents being as the load distribution will be thrown askew during agitation. Replacing the agitator should have resolved the problems related to it. Is the load really off-balance? Do you redistribute the items before restarting? Can't say if it's part of your problem without examination ... the tub support rods can get worn after some years of use and cause excessive off-balance occurrences. Replacement is fairly easy and they're not overly expensive, approx $80 for a set of all four rods.

I know you said you checked the circuit, but just to be certain: is the electrical outlet for your washing machine being fed from a nearby GFI outlet that has been tripped?