I'll presume you didn't fully backup your hosts root file systems on the host which was fried.
It may be easier to replace with a new hostname/IP.
I would focus on the gluster config first, since it was hyperconverged.
I don't know which way engine UI is using to detect gluster mount on missing host and decides not to remove the old host.
You probably also have the storage domain "mounted in the
data-center" with backup volume servers pointing at the old host details
The remaining gluster peers also notice the outage, and it could be detecting that?
I would try to make gluster changes, so maybe the engine UI will allow you to remove old hyperconverged host entry.
(The Engine UI is really trying to protect your gluster data).
I'd try changing the mount options and there is a way to tell gluster to only use two hosts and stop trying to connect to the
third, but I don't remember the details.