When I turn the key, the green light is on (so there is power) but as soon as I press the brake, or turn on the lights, the green light goes off and then when I turn off the lights or the brake it comes back on but very dim. I thought the battery was dead, so I hooked it up to a charger, and still the EXACT SAME THING!!

So it gets power, but when I try to start it or do anything the green light just turns off and nothing happens. I am so confused... even with the charger attached this is still the problem.
This all started while I had the charger attached and I was boost starting it. It was turning over fine, for a while, and then it all stopped. I checked the main fuse that's right by the battery and it is still intact. How could the green light come on, but it doesn't start and the lights don't come on?
One problem is literally leading to another! I was boosting it because i was trying to start it and the battery died in the process. I think the carb needed to be adjusted, which I found out here, AFTER it stopped getting power.

Anyone please help!!