After new 5TB drive installed, drobo no longer working properly.

I installed a new 5TB drive, the drive was red went red immediately, but then the drobo began green/yellow blinking, which I took to mean it had recognized the drive and was rebuilding.

After the rebuilt cycle, all lights green.

After an hour or so, the drive went red again, and and the drobo repeated the process of the yellow/green again.

Now the drobo shows all drives as green, but won’t mount.

Not sure what to do.

I could replace the 5TB drive with the 2TB drive I originally had installed, but I’m not sure if it’s a larger problem.

Help me Drobo S community.

Check the obvious first… Are you running a FW that supports >2TB drives?
Drobo S: Min Firmware 2.1.0

Could also be the new 5GB drive has a fault.
Maybe run it through a HW check with something like Spinrite.