The original HomePod, announced back in 2018 has had a number of issues relating to software over the years. Both the original HomePod and the HomePod 2 don’t have a USB cable, which means there isn't a simple way of plugging the device into a computer to restore it. When the HomePod mini was debuted, it was fitted with a USB-C cable, meaning if any issues arise, it can be restored using the Finder app on macOS, just like an iPod.
However, over the last few years a lot of users (myself included) have been unlucky enough to have their HomePod units bricked and Apple is never willing to fix them. However, HomePod specialist from the US, Nic's Fix has finally found away to restore them if they become bricked. Apple's solution to this problem has always been to throw it out and the customer can buy a new one, albeit at slightly less than retail price.
Nic published a video going over how this can be achieved. As it happens, the HomePod has a hidden proprietary connector hidden under the base, Apple usually uses this for diagnostics but Nic has custom made his own adaptor which he now sells online.
It is worth mentioning that this solution won't work for every HomePod issue, as not every problem is software related. Some HomePod problems can be hardware related and it won't be possible to know without using the adaptor and plugging it in to a computer.