Sarah,
The switch may be encountering the following issue in which EXOS loads a configuration file (.cfg) that has SSH enabled, but the switch doesn't have a SSH key in the eeprom. Please review:
https://gtacknowledge.extremenetworks.com/articles/Solution/Why-does-Enter-passphrase-show-up-during...
If this is the case, then we made need upgrade using the BootROM method to address xos0064864. Note that this method would wipe configuration.
You can also try to switch partitions and Boot of a different version using the BootROM. Once in the BootROM, select "boot 1" or "boot 2".
We should certianly try to recover the switch before we look at RMA options.
Let us know if this helps.