!WARNING! Wall of text mode has been engaged!
They are both soldered super tight to what seems like a heatsink, so I cut the legs and tested them with my DMM on the 2000K setting.
By just this, I don't know which legs you tested exactly, I'm assuming your doing the two you cut off the board?
One of them registered 1235, but with the probes reversed registered 1 (as though the probes were touching nothing). That does not make sense to me, so I did it a number of times with the same result. The other registered 1, reversing the probes also registered 1.
You can call off the exorcists and Steven hawking, nothing is possessed and no laws of physics were broken, this is just the diode effect. Diodes only allow electricity to go one direction, like an electronic reed valve. A transistor is an evolved form of a diode, so these results are hardly surprising. These numbers could be a good BJT, or a bad FET. Or possibly a good FET *IF* you did your test differently than I am currently assuming.
In any case, we are most likely going to have to start over again, since I'm not sure exactly which legs you were testing (The crystal ball is getting more smoke put in it right now)
Just as KeepItSimpleStupid has said. There are three(3) leads to those black things, they are most likely FET's... just as what you have been using for your pump circuit. Same gift, just a little different wrapping paper is all. The important thing to get is that the metal tab that is soldered to the heat sink is ALSO the middle pin. I have never seen one that was not this way, but I'm sure they could do it. (If they wanted to be really mean to us that are used to whats normal)
First test:
I want you to test the middle leg to the right leg and swap the probes back and forth if you would. A good part should MORE OR LESS conduct electricity one way (probes healed together), and not conduct the other way (probes held apart) with this test. The way that conducts will likely not show up FULLY conducting with a DMM. It will prolly read a few hundred ohms or so instead. If not, use KISS's test instead.
Second test:
Test the left leg (right leg in your first picture) to BOTH the other legs, and also swap the probes back and forth on that test as well. A good part will
*NOT* conduct electricity (probes held apart) at all with this test. Any thing less that ~100,000 ohms is bad. (most of the ones I just tested were greater than my meter could read)
You will be testing BOTH parts, with EACH test. So four(4) tests in all.
Also note, you *MAY* need to use something different than your DMM as some meters are finicky for FET testing. However, this is all I ever use and it has never failed me. Then again, I also know what exactly it is I'm looking for and I have a meter with diode testing function. If you get odd results, build the circuit that KISS suggested. It works better in some ways than a DMM.
Also, it looks to me like in your pictures that the heat sinking is actually unetched copper the manufacturer left on the circuit board just for heat sinking reasons (very common). Or is it that it's an actual full blown metal heat sink under there some how? If it is a full heat sink, like
a large piece of actually separated metal then the black things *MAY* be BJT's and not actually FET's. I find this unlikely but I exclude nothing. If you could read us the numbers off them, that would be even better. After you clean them off, if they are hard to read, a little acetone makes them REALLY stand out clearly. Try not to use acetone in an enclosed space, unless you have something really cleaver you want put on your head stone. But you prolly already knew that
Here is another YouTube video for you. This one is on testing MOSFET's. It kinda sucks, and I may make one of my own and upload it to YouTube myself later, (if I'm not still really lazy instead). Suck or not though, it's correct and should help you sort things out a little. *REMEMBER* THE METAL TAB IS THE MIDDLE PIN ALSO*.