PON light went off a day ago

[Curious sage]

Hi I have a Huawei ECHOLIFE HG8145V5 router connected to bsnl Bharat fibre network. The pon light suddenly went off yesterday and the los light is also off. I tried resetting the router but the issue persistent. Today I reset it again with the fibre disconnected and the router los light worked fine, but as soon as I insert the fibre, pon blinks and few times and then goes off. Tried multiple times same result. Optical power is at the prescribed levels. Can anyone pls help?