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Sure Signal 3 not working following powercut - initially failed to make reconnection, but, now no lights showing and wont reset
Please unplug it now if you haven't already and then phone customer services on 191 or Live Chat and they can help replace it under the 24 Month Manufacturing Warranty.
If it's over the 24 months then as there is a known issue with some of the v3 units then if yours falls within that they will replace this for you.
You should not need to upgrade your contract to be able to get a new Sure Signal.which is what some agents are trying to instigate.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.