Remove inactive volume to use the disk. Disk#2,3,4 (again)

Hi

I recently had this incident: 

https://community.netgear.com/t5/Using-your-ReadyNAS/Missing-volume-after-power-failure/td-p/1246361

and by miracle the system came back up.

So I did a backup to amazon cloud with the most important stuff and replaced the faulty disk (sdc) with a new one.

The system started to sync and after a while I got:

* Disk in channel 3 (Internal) changed state from RESYNC to ONLINE.

then

* The resync operation finished on volume data. However, the volume is still degraded.

then

* Volume data health changed from Degraded to Inactive.

And then the system froze.

After a reboot I was back on square one with "Remove inactive volume to use the disk. Disk#2,3,4"

So what gives?

Is my data really lost this time? Is the NAS breaking my disks somehow?

The only disk related error I can find is on sda and "Current Pending Sector Count:   4"
I downloaded the logs if it can help.