"...your alarm clock is open..."
6 commenters point out that "open" is not the 'right' word to use here. Other suggestions are "on," "set," "turned on," etc.
So: what kind of situation is this?
You can call it a 'direct translation' error, assuming the student is "thinking in Chinese" where 关 means both open (like a door) and turn on (like a light or appliance). So he incorrectly translated guan - he picked the wrong meaning. (But maybe he didn't know that it can be translated as 'turn on' at all.)
Similarly, you could call it 'interlanguage' or 'interference' from Chinese, both of which would also refer to the situation above.
If you didn't want to think about it from an SLA perspective, you could call it a 'word choice' or even 'collocation' error -- any time you write, you can pick whatever word comes next, and in standard English we wouldn't expect an alarm clock to be 'open' but we would expect it to be 'on.' It's not necessarily directly because of Chinese. (It probably is, though, but you can't always prove that. Plus, other NNESs might use it.)
We could go so far as to call it a 'variation,' (that is, a legitimate dialectal difference from standard English) because it seems to be attested that open/close for things like lights is pretty widely used by NNESs. (I know some people who use it.) (see this Google search.)
I guess the most likely (I want to be careful about ascribing intent to the writer) is the 'direct translation' scenario. The commenters are more generally calling it a 'wrong word choice,' and I'm personally sympathetic to calling it a variation. Who's right?