Red LOS means the ONT can't see the light from the OLT or something weird has happened with the firmware on the ONT.
Have you tried resetting it by holding the button at the top left for 10 seconds (I have one of the older Huawei ONTs but I'd imagine there's a reset button somewhere)
Virgin (ADSL) => Namesco => Newnet => O2 => Plusnet => Zen => Newnet => Zen => Freeola => Vivaciti (using O2 Wholesale DSL) => Xilo (C&W Wholesale) => Xilo (O2 Wholesale) => Xilo (TT Wholesale due to O2 Wholesale closure) => Zen LLU =>> ZeN FTTP (Openreach 300 Mbps down, 47 Mbps up)
Router: Fritzbox 7530
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.