OK, lets correct a few things. BLACK transmission fluid, especially if it smells burnt, will not be fixed with a solenoid.
Black transmission fluid is black because it got hot, and the clutches degraded and bits of clutch material are now shed into the trans fluid. The transmission clutches are worn out/damaged, When there is NO material, it will no longer apply properly. IE- slipping in 1 or more gears. If its computer controlled it will likely go into limp-home mode and start and stop in a single gear (usually 2nd or 3rd on cars, big trucks it may be 4th or 5h even).

This is a toyota forum, so be aware, toyota does some descriptions oddly. They say ELECTRICAL FAULT. IE - P0753 shift solenoid 1 electrical fault. That normally means power/ground/resistance. Something wasnt as expected when an electrical command was given, In toyotas case, solenoid 1 commanded on means 12v was sent from the computer to solenoid 1, a specified resistance in that solenoid (12-15 oms in this case) would cause a load of 1 amp on the computer. While the computer holds that, the soleoid will be ON or ACTIVE and the fluid will be directed or blocked to a given passage. Toyota does not ALWAYS identify electrical properly. They measure the solenoid amperage to be 1 ohm based on current flow. If it isnt, it will set a p0753. BUT, they recheck it by pressure switch, RPM change and variation between input and output speed sensors suddenly changing, If those things dont happen EITHER, you may get the 753 code, but the problem may be a bad clutch, a leaking O ring seal, low fluid even! Toyo does this more than others (Uses the word CIRCUIT or ELECTRICAL in a code, but non electrical things can still set that specific code).

Keep it in mind. Changing black oil can be good, but it can also lead to immediate fails. If the system is compromised enough for the oil to be black, the oil is also worn out. Its detergents are no longer working, its thinner than it used to be. Replacing it with fresh fluid will sometimes raise pressures enough that it pushes the borderline parts over the edge so to speak. They were already dying...dont believe anyone who says the oil change wrecked the trans. It was already wrecked. It just showed it right after because of the increased pressure of new oil.

If I were chasing a 753, Id look at gear command on a scanner, when it commands solenoid 1 ON, do I feel an RPM change, (see it on the tach), does it change again when it commands off? does the solenoid ohm check in range 12-14 ohms (or whatever your specific one requires)? are the connectors clean and tight?

pattern fails are guesses. Fix a car with test and diagnosis. Not JUST DO WHAT FIXED THE OTHER GUYS CAR...THAT ALWAYS WORKS.
Test YOUR car. Fix based on what is found.