Pontiac Repair: Battery Light, oxygen sensor, running lights

Question
Hi Larry, a mechanic did some work on my 19996 Sunfire he changed what he said was a bad starter (I never had trouble with it before he said it was bad) also the engine light on (WHICH IS WHY I BROUGHT IT in) he changed the oxygen sensor and re-programmed the factory installed security system (I do not not have the "clicker" for the door locks).  Now I really don't know what's going on, I  stopped at the store then when I tried to start the car it would kick over and then stop the  "security system" light would come on.  I disconnected the battery several times for different lengths of time NO Good.  Then after about 1 1/2 hours it just started.  In driving it home every idiot light was flashing, the running lights were flashing, the tach was jumping all over.  Now the 'Battery light' is the only light on, what is this light trying to tell me--Bad battery, alt or what?  Please any help.  Just a side note I had my car in to this mechanic 3X(s) for the original problem of the engine light on and he would fix it for about 10 miles then it would come back on.  That was the only light that didn't come on in the last episode.

Thanx

Doug

Answer
the check enhgone light can come on for many reasons he prob would just reset it and then later it would come back on,, but as far as your current dilema it sounds like you have 1. aloose cable on the batter or starter, 2. dirty cables on the same. 3. a shorted wire , 4. or bad alternater.. id stop in at a local shop and see if its charging?  low voltage cando alot of weird things when it is below what is needed to run the car, id start there