New fibre fitted yesterday not working

[Pickle1234]

We had sky fibre installed yesterday by an engineer. The broadband was working fine this morning, then suddenly it cut out. 

I've restarted the hub several times (just a green light on power and wifi-no light on internet or voice)

I've restarted the ONT.. It has green light on power, red light on LOS no light on PON and flashing green light on LAN

any help or advice appreciated to get us back online! 

[JimM1]

@Pickle1234 Red light on the LOS is bad, the fibre to the exchange is down, if it's engineer doing a change that may cause, but if not login to your account and run the service checker.