Paused de-encryption MB Air frozen at login - solved

I am posting this because none of the many answers in other questions either here or across google land solved it for me, until now, after three days with my MBA basically bricked - thankfully I have two backups, but prior to that Time Machine refused to back up (before the total freeze related to "scanmanager error" from Verbose mode ) because of the same issue, so Superduper! saved the day here as well.

My MacBook Air running High Sierra, (encrypted because of GDPR), then part decrypted and "paused" (despite power connected) and no amount of terminal commands or diskutil unlocking made any difference, even disk erase etc all failed until I found this:

http://www.mactricksandtips.com/2014/01/check-enable-and-disable-filevault-from- terminal.html

The key part of which is (in case the link ever breaks) with grateful thanks to

Knut Ahlers

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But there is a much more simple solution if you don't need any of the data stored on the harddisk: You can boot the MacBook from an OSX-USB stick (hold Option while booting) or the recovery partition (hold Cmd+R while booting), then overwrite the "GUID Partition Table (GPT)" with a MBR which will destroy any information read by the installer to identify the harddisk as encrypted. After this the disk utility is able to erase the whole disk and prepare it for a new OSX installation.

To do this follow these steps:

1. Open the Terminal from the Utilities menu in the recovery boot
2. Search for the harddisk to erase using diskutil list (copy the device name like /dev/disk0)
3. Write a MBR using fdisk -i <your device name>
4. Close the terminal (Cmd+Q)
5. Open the disk utility and erase the harddisk
6. Start a new install of OSX

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Then a Superduper! restore and it seems all is well.

I hope this helps someone like it did me.

Anthony