You can repair the drive in Linux using a utility called Test Disk. Best to try that first before reformatting the disk. Fairly simple process too.
Interesting. It has been a long time since I’ve had a computer with a Linux installation. I think that the Arris box has an OS way closer to Linux than Windows but is it close enough for a Linux OS to repair an Arris box hard drive format?
In any case what I did by removing and unpartitioning the drive is beyond most people’s comfort zone, as is removing the drive and repairing it using Linux.
The bare minimum you need to get the box up and running again is a suitable screwdriver and a new drive.
Whilst I knew from a web trawl the Torx bit set I needed I decided to go to a hardware store - a real one with a counter and helpful assistants - with the box. With the help of the man behind the counter I bought a screwdriver that fitted, designated as a TX10. Cheaper than the set and available immediately.
As for the hard drive the Arris box had a 500gb 2.5“ Toshiba drive but was happy enough with my Western Digital. Amazon sell the Toshiba drive for about £12 but bigger drives (max 2gb) are available. Given that price starting point buying a new drive makes more sense if you don’t have a suitable usb enclosure or access to a computer.