You need a new battery.

You can get Torx drivers at a hardware store or lumberyard.

The trickle chargers only work on batteries that have some charge. It's nice to have a "real" battery charger around as well, for situations like this. If you've got a harbor freight nearby, you can pick one up for ~$30 that has a mode for small batteries like on a bike.

I ran my bike's battery down with the lights, and it ran weird until I charged it all the way up with a (non-trickle) charger. I'd try that first, then buy a new battery.

If the shop'll do the work for free (because it's so new and under warranty maybe?) let them figure out what's wrong.

'borrow' battery from motorcycle owning friend?

Yes, buy a new battery. It's probably an open circuit, or (less likely) shorted out entirely... some kind of broken connection inside, perhaps.

It definitely sounds like a bad battery to me. Bad as in not taking even a trickle charge. Bad as not even allowing current to really pass through it and allow the altenator to keep the bike running.

I would buy a new battery and install it.

Given those symptoms (and your earlier ones), I'd actually guess that somehow the wiring to the battery (or between the battery and the engine) has come loose. I'd not expect a motorcycle battery to suddenly read completely dead (even leaving the lights on is more likely to leave the battery reading a low voltage, rather than zero volts). But zero volts is entirely consistent with "disconnected".

So I'd suggest you obtain the necessary Torx tools, pull the battery, and test it individually (and perhaps charge it separately -- as others have said a trickle charger works best if the battery is already partly charged, but in general if it's been completely discharged it may well need replacing anyway). Worst case you discover the battery is completely dead and you get a replacement, for which you'd have to have removed that cover anyway.

I tend to agree with your shop that the alternator is unlikely to have died in such a new bike, and generally they get less efficient (and thus charge less efficiently and start less efficiently -- it's also the starter motor) rather than just stopping working.

Ewen

I agree. Not only is it unlikely that the alternator is bad, but it's equally unlikely that the battery is bad, after such a short life. I don't know why the shop didn't say so.

Sounds like the battery has a dead cell. It'll never charge. Essentially an open circuit.

Call the dealer and tell them you have a brand new dead bike. A decent BMW dealer will come pick it up and repair it for you under warranty. It's probably just a faulty battery but while under warranty let them deal with it.

I have to agree. however, batteries are not usually covered under that type of warrenty. I would just take the battery out (torx drivers are part of any good toolkit) and take it to whatever auto or battery store sells that brand battery. ask for a replacement as most batteries like this have a 5 year warrenty.

I had a new, but discharged, battery do this with a modern charger. I found a random 12V 1A power supply (a wall-wart), clipped the plug and connected it across the battery terminals (same polarity) and used the (unplugged) charger clips to hold the wires in place. Obviously disconnect your bike battery leads first, and don't leave it unattended or it might boil your battery.

After about 20-30 mins of this there was enough charge in the battery that the modern charger would now charge it. That battery is still going strong 3 years on.

An alternate method would be to find someone with an old-school 12V charger containing no "brain".

Urgh, annoying. You might try leaving it on the trickle charger overnight. If it's way way low it might pick up enough while on it that long to get charged again. That's the nice thing about trickle chargers, they're meant to be used for a long time.
But yeah sounds like way dead battery. I'm surprised your BMW shop isn't offering to come get your bike for you, they usually give rock star treatment.

Email me his contact info.

Totally discharging an automotive battery destroys it and it will no longer hold a charge (really all batteries, but automotive ones are more sensitive since they're designed to provide high bursts of current). You'll have to replace it.

yeah... it forms crystals all over the plates and when it's completely crystallized, it's basically "petrified".. no charge can be reabsorbed.