There should NEVER be a need to try all four slots on any dual channel consumer motherboard. If you are using two DIMMs, they go in the A2 and B2 slots, period, no matter WHAT motherboard it is, if it is a four slot board and is a dual channel architecture. Those are the second and fourth slots over from the CPU socket and on some boards are called DDR4_1 and DDR4_2 but are still in the same locations.
If you cannot get normal memory function in dual channel at full speed using those slots then there is ALWAYS either a problem with the memory itself, or the CPU, or the CPU socket pins, or a CPU cooler that is either TOO tight or tightened unevenly at all four corners or from one side to the other. There is no reason to EVER have to use any other slots unless there is a physical problem of some kind and if there is then it needs to be resolved. Using a different slot is only ever a band aid.
If you have only one stick of RAM, it should be installed in the A2 slot which is the second slot over from the CPU socket going towards the edge of the motherboard.
It's also possible that you have a bigger issue that was right on the edge of having a breakdown, and tearing it down simply pushed it over the edge. We see this happen with motherboards all the time when they are five plus years old.