2002 Cadillac Deville DASH READING LIGHTS STILL ON AFTER RE

GENTLEMAN: MY DASH BOARD COMPUTER INDICATED, BATTERY NOT CHARGING, THE SMALL RED BATTERY INDICATOR ON THE LEFT SIDE IS LIGHTED UP. TAKEN THE CAR TO THE MECHANIC HE CHANGED THE ALTERNATOR AND REPLACED THE BATTERY IN THE BACK SEAT. NOW HE SAID THE ALTERNATOR IS SURGING HIGH AND CAUSING THE BATTERY TO BURN OUT, ALSO HE CAN'T SEEM TO GET THE RED BATTERY LIGHT TO RESET, ALSO HE SAIDTHERE SEEM TO BE SOME ELECTRICAL PROBLEM WHICH HE CANT FIND WITHOUT TAKEN THE ENGINE OUT AND CHECKING EVERY ENGINE WIRE. ALSO CHECK ENGING COOLANT KEEPS COMING ON THE COMPUTER SCREEN, BUT THE RESERVOIR IS FULL AND NOTHING IS WRONG. HELP PLEASE.