Help Lil Bastard

[clb0099]

I am what I think might be a minor problem but not sure...

Ok I replaced my alternator with a Bosch one since my alternator was trashed. I also recently bought a Optima Red Top battery R34 about two weeks ago. When I first installed the battery about a week or so later the car was idling in my driveway and just plain out died. So my friend tested the alternator and found it to be no good and that I was just running on the juice of the battery and it was not recharging. So after replacing the battery my friend got this idea to see if the alternator was running good so he put a tester on it and it came up basically alittle over 800 cold cranks. He also stated that my car should run off my alternator if he pulled off the positive cable of the battery terminal. So with that he did it and the car died instantly. Is that true that it is suppose to keep running?... Well after reconnecting the battery terminal I restarted the car only to find that my cluster looked like a christmas with all the lights on. The lights that are on : TC, Triangle with exclamation in the middle of ,Abs,and a picture of the battery.... I know for sure that the lights were not on before swapping out alternators but not sure if the lights were on before he disconnected the positive terminal while the car was running.
I then ran a Durametric software to see if there were any error codes. Nothing came up at all expect the passenger seatbelt buckle and that is because the seat has been removed from the car in order to do the alternator. The lights are still on after running the software. I then went to check out the battery voltage by putting on a battery maintainer which showed that the battery was half charged not sure why but it was... I have at this point have the maintainer connected to the battery to recharge it... Any ideas what the hell went on? I mean ..There is no codes on ecu but the cluster lights are on ?