BeCM problem

Hello to everyone, new to site.
History so far - I have a Range Rover P38. I was travelling along no problems, indicated to turn left and suddenly all instruments went blank, the audible bleeping noise was continuous, pulled over stopped engine, wouldnt start again battery dead flat. Got vehicle home, no instruments, no electric windows, seats wouldnt move and it appears that the left hand side of the vehicle had 'suffered a stroke'. All the fuses appear to be intact except the 60amp fuse on the brown and green wire going to the BeCM. Once battery had been charged up the engine run perfectly well the vehicle is also fitted with gas conversion. Have removed the BeCM from the vehicle, there is no corrosion for any of the terminals, has it completely failed? would appreciate any ideas. Look forward to any help/ideas. Pete

Well, to start with, something is going on with the battery going flat. That could be a bad battery, a battery drain coming from ? or it's not being charged properly. The BeCM on the P38 is known for going wonky with voltage fluctuations. The burnt fuse I don't know about.

Thanks for speedy reply. I checked the charging with multi meter, it appears to be charging ok. I think the engine was running on the power generated by the alternator, because somehow the battery had been drained during the journey. This is why once the engine had been stopped it wouldnt start again. The battery is 4 years old but appears to be ok, I charged it up and its holding its charge.

Try checking the voltage of the battery before starting, then the voltage idling, then under load with the lights and heater on. Idling should be a bit above 13 volts, under load 14+.

Also check your battery earth.