Electric water Heater Smells Like It's Burning?

Yesterday while taking a shower, I noticed that I lost my hot water quicker than normal. I didn't really think anything of it, but later in the night realized I still didn't have any hot water. I inspected the rest of the faucets in the apartment, and no hot water to be found. I called maintenance this morning, and they came out and fixed it. They didn't tell me exactly what they did, but said that I should have hot water again in about half an hour. I went upstairs, and about 20 minutes after they left I began to smell something burning. I came down, and sure enough it was coming from the water heater, but I couldn't see any smoke and nothing felt hot-- just smelled like burning. I flipped the breaker switch to the heater and called maintenance back. They returned, said they couldn't find anything wrong, but changed the thermostat as it was the only thing they thought could be causing it. They left (leaving the 2 cover plates off for reasons i dont know, just said "don't put your fingers in there"), and now its about an hour and a half later, and I can still smell the burning. It's no worse than before, and again, no smoke, it just seems like it never went away from before. Should I be concerned about this, or is it just a residual burning smell from whatever caused it earlier in the day? At what point should I worry that I can still smell the burning?