The 50C measurement is is not the drive, but rather for the surface temperature of the main player circuit board underneath the drive. It is very possible and probable that the drive itself will be 5-10C warmer than the measurement of the circuitry below, exceeding the acceptable working temperature,s and thus producing failures.

There've been more than enough reports of "it works with the cover off" and "fails with the cover on" to substantiate this, though one will never know for sure until we measure the temperature at the drive itself.

Cheers