I bet this is a bug...
I doubt that you busted the sensor, it's quite robust and well protected. The batteries should be well enough sealed for short-term use.
Nope, my suspicions were aroused by the maximum altitude figure of 32707ft, which, as any fule kno, is close to the upper limit of 32767 for a signed 16 bit integer. Any more than that and the top bit will be set, which will make the value negative. What happens after that is up to the software.
This time RTFM could be misleading; the MS5534 datasheet says 'All calculations can be performed with signed 16-Bit variables.' Maybe so if you deal only in metres.
You're not the first to be had by this one, I found in 1986 that FS II on the Amiga would fly into the ground if you set the autopilot for more than 32767 feet, and the first Ariane 5 launch was downed by almost exactly the same bug.
You might need to reset the thing to get back the calibration data, but it's probably not broken, unlike the Ariane. Have fun!