Hi @stu4jc ,
Check if the fuse in the player has blown.
This link may be of some help with the fuse. Unknown type of fuse?
Here’s a link to the ifixit Sonos Play 5 guide(s) which should help you in opening the player.
If the fuse is blown then there is always a reason why. Check the motherboard for any obvious problems such as burnt out components or blown capacitors.
If you do spot something and you are unsure post some pictures back here. Here’s how to do this iFixitでの質問に画像を追加する方法
If nothing is evident you may have to get technical with a DMM (digital multimeter) to find the reason.
I tried searching online for a schematic diagram for the player to make life easier, unfortunately with no result. You may have better luck.
If the fuse is blown, order a couple of replacements just in case the new fuse blows as well.
If the new fuse holds and the player is working again, it may have been a case of fuse fatigue.
Good luck with the repair.