So we would need some more details.
When I do this, I remove the disk I want to replace from the pool in unRAID by stopping the array, removing the disk then restarting the array. ZFS reports the pool is degraded and a disk is missing. I then stop the array and physically replace the drive ( I don't have to power the server off as I have hot swap drive bays) once the new drive has been added to the pool to replace the old one, I start the array. At this point ZFS should detect a new drive to replace the missing one and automatically start the resilvering process.
What do you mean when you say it shows disk 2,3 and 4 as wrong? Wrong how?
Are you sure the resilvering process was completed before you replaced the last drive?
Did you check the logs in unRAID for any info.
Do you have a backup of your data?