Power light flashing

[Sallyr1]

We’ve just had a severe thunderstorm, all other electrics are working and I've changed the modem to a different socket but light still flashing

[caesarome]

@Sallyr1 

This explains the lights on the hubs:
https://www.sky.com/help/articles/hub-lights-explained-start

[Deb3000]

You don't make it clear if by "modem" you mean the ONT, (the fibre box on the wall), or the router.  You also don't indicate what colour it is..  Anyway...

If it is the router power light, flashing green suggests it's trying to do a firmware update.  Flashing amber means it is in recovery mode and needs a factory reset with the little button on the back.

For an Openreach ONT, flashing green is normal start up, (not if it's stuck, obviously), or a firmware update.

For a Cityfibre ONT flashing amber is a firmware update again.