So, when I got home yesterday, I found that my Samsung microwave was beeping frequently for no apparent reason. Switching it off and back on did fuck all and occasionally I'd see the clock display read "5E" or "SE". This issue didn't go away even after a few hours and I'd resigned myself to having to go through the rigmarole of calling a service center and getting this fixed which would undoubtedly involve charges amounting to a good chunk of the microwave's original price. Of course, that wasn't what I did. I slaughtered a lamb and checked its entrails and they informed me that I must consult Google immediately. So, I consulted Google immediately and it informed me that the "SE" was very likely a "Short Error" with keypad and I simply needed to clean a small ribbon that connected a board to the keypad membrane and I would be set.
So I disconnected the power cable to open up the microwave and lo and behold, said flimsy ribbon was there. I removed it carefully, gave it a wipe, and firmly stuck it back in and voila! the issue was fixed.
I should note that you need to be careful to not touch any of the other components inside the microwave. Even though the cables have been disconnected, some capacitors might retain a lot of charge. Be safe.
This video displays the ribbon in question. Unlike in the video, I did not have to open up access to the front panel's control board. I could access it fine once I opened the chassis of the microwave.
Hope this helps!