If the light on top doesn't work, you have a power issue. Use another power cable to be sure that the device itself has an issue.
Opening the device (as explained elsewhere on this site) will void warranty and possible support from Sonos.
Inside, on the motherboard, there is a fuse, which can be replaced only by desoldering it.
See other questions regarding this device: if you didn't have a high tension peak in your electric installation, it can be the thermistor (TH301) which has failed.