G650GS Sertao Starting Issue Since Flat Battery

My GS Sertao has been stood since the end of March. I tried to start it a couple of days ago but (unsurprisingly) the battery was flat. I took it out and charged it, put it back yesterday but the bike will not start:

Key in, ignition on, dials spin round, dash lights check all OK.

Press the right hand button on the key fob to disable the immobiliser, it beeps 4 times (never done this before). Press starter nothing happens. Normally at this point the bike should start.


I read that the 4 beeps means that the battery has been disconnected, which partly makes sense as it has but I would only expect this to have happened the first time the bike was switched on after the battery was put back in and not to stop the bike starting at any point.

One thing I have noted is that when I normally press the button to turn off the immobiliser l hear a short buzzing noise this is not happening. It has been suggested this is the fuel pump priming (or not in this case). If the fuel pump has developed a fault would the starter still turn or would the computer stop it?

I also read that the immobiliser has it's own small battery which charges from the main battery, this could have gone flat. I am currently hoping this is the case and the bike will start when I try it later. Although I am not that optimistic!.

I have checked the kill switch is not on - it's not!

Has anyone had a similar issue or have any ideas?

Many thanks.

Try shorting across the terminals of the starter solenoid to eliminate that first and check your fuses in case you shorted a cable while fitting the battery.

Put a volt meter on the battery, is it well over 12v and does it change when pressing starter button.

Clutch switch if in gear etc etc

Sorted

Thanks for your help it's sorted was a knackered battery. Gave odd readings on the multimeter. Swapped it out started first time.