Car won't start after replacing alternator... on 1998 BMW 323i

i Have a BMW 323iC. I had a guy replace the alternator (it was dead & had been draining the battery previous to it finally dying). The alternator now works, the starter seems fine, everything engine-wise seems fine...but the car will not start. The BATTERY LIGHT is on, the OIL light is on & the EXCLAMATION MARK (inside sort of a circle) is on.

What could be the problem? Please help!

Asked by for the 1998 BMW 323i
The alternator does not assist in the starting of a vehicle, only provides power to electrical system and charges battery during engine operation.
If the alternator was indeed failing, the battery would have been completely depleted of energy as the alternator could not output to keep the engine/vehicle electrics running.