Can only boot using rescue kernel

I’m not sure where you get that impression, bug reports I’ve seen regarding this are from back in 2008/9.
This smells like hardware failure to me - SATA controller or disk failure.

Have you tried just a yum update?

Failing that, you can force rockstor to recognize your particular Kernel version as mentioned by @phillxnet in this thread:

That should at least clean up the errors regarding the Kernel version, however it should be noted that I think this check exists to ensure that your Kernel and btrfs-progs are in sync.

I don’t think it will be dangerous to alter this, however it may be prudent to wait for developer feedback.