If you did not have ANY similar error issues prior to starting the system with the memory halfway installed, but did after, then of course it stands to reason, and there is much precedent to support this as we see this happen here and there, that you've in some fashion either damaged the memory or the motherboard. Even the CPU is vulnerable since the memory controller is IN the CPU, and can be damaged by the memory circuit if there is a short or other issue.
My main question would be whether or not you had the CPU and CPU cooler, or any other hardware besides the memory, removed at the time you did the "cleaning"?
First thing I'd do is make sure ALL electrical connections are completely seated, remove the RAM again, make sure you have the population rules correct with the memory in the RIGHT slots for how many modules you have installed based on the motherboard manual population rules (YES, this makes a difference. Most systems CAN run without following the population rules but with varying results including lack of dual channel operation OR errors.) and then reinstall the memory, making sure they are in the correct slots. Every board is different so check the manual.
If all of that is good, try running only a single stick in the slot intended for single module operation to see if there are still errors. Then try the other stick by itself. Let us know what if any changes you notice or if it's the same regardless of whether or not you use either module or both/all, IF you have more than one memory module that is.