Other cameras' images are normal both in daytime and night, but one or several cameras' image is abnormal, such as fuzzy, flickering,?snowing,?staying black and white in daytime and so on.
1. connect camera C1 to channel A1 with? working cable B2 to confirm if there is issue with cable B1
2. Connect camera C1 to channel?A2 with working cable B2?to confirm if there is issue with camera C1
3. Connect camera B2 to channle A1 with working cale B2 to confirm if there is issue with?channel port A1
Please try all methods above to confirm which part is wrong so that we can give you correct replacement.