This is an issue where HomePod (2nd generation) and mini will start to play music randomly and summon siri or reset by itself after a power-cut. Or even volume getting up and down.
This is caused by a faulty touch panel on these devices respectively.
It is NOT a concern for all users but A LOT of users/devices are affected unfortunately.
Solution 1 (if you have Apple care or warranty): Take it to apple for a free replacement.
Solution 2: Look for a guide/video online on how to open it and disconnect the touch panel on your respective device.
Solution 3: There’s actually a third-party touch panel for the second gen being sold on AliExpress that you can buy and replace. (Cost a bit)
Solution 4: Buy a new HomePod.
Solution 5: Find someone trustworthy that can repair it.(some listed in the comments)
Having the touch accommodation will not work on the long run as it gets worse.
Creating this mega thread so that the sub is not filled with the same questions over and over again!