What can turn on the battery light in the car other than the battery and alternator?

My car is a 96 ford contour. The car was perfectly fine when all of a sudden the battery light on dash started to flicker. When we parked the car at home and attempted to turn back on the car wouldn t start. Tried it again nexed day and at the first try car turned on but battery light remained on. When turned off and attempted to turn on again car wouldnt start. We went and checked the alternator and were told that regulator wasn t working. So we changed the whole alternator (just in case). We checked the battery and were told battery wasn t holding charge. So we bought a new one. Battery light is still on. We cleaned all possible corrosion in wires on alternator and battery but still light is on. We are at a stand still any ideas of what else we can check?

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