Best way to jump start a dead battery? E85 Z4

E39 owner here. I've been asked to jump start my friends Z4.

Even new, the car has had a marginal battery. But after sitting in a cold garage for a month, the battery can't crank the engine. Cluster still illuminates.

I know the battery is in the trunk, but I've read that there are jump terminals under the hood.

I'm not sure if there is a negative terminal under the hood. If not, any ideas for best negative location ?

Thanks!

Positive 'boost' terminal is on the firewall, offset a little to the right side. Negative terminal is on the right side of the engine compartment, near the middle of the fender. Both are high up and pretty easy to spot.

On my 08 si the positive terminal is up on the firewall center(under plastic cover) and the negative terminal is on the driver side fender well

West, you beat me by seconds!!

It's my new turbo mouse 9000 ....

Thanks Guys!

I have NOT had good luck jumping BMWs.

I have found that I need to either charge the battery or replace it.

His car probably went into transport mode, check if the ac are blowing full blast or not.. he may need to go to the dealer to get that reset