import re
text = "A1 AAA....A1234!!!!~A123A abc,AAAAAA,123,A,1,A1B2C3"
print(re.findall(r'\b(?=[A-Z0-9]{2,5}\b)[A-Z0-9]*[A-Z][A-Z0-9]*\b', text))
aW1wb3J0IHJlCnRleHQgPSAiQTEgQUFBLi4uLkExMjM0ISEhIX5BMTIzQSBhYmMsQUFBQUFBLDEyMyxBLDEsQTFCMkMzIgpwcmludChyZS5maW5kYWxsKHInXGIoPz1bQS1aMC05XXsyLDV9XGIpW0EtWjAtOV0qW0EtWl1bQS1aMC05XSpcYicsIHRleHQpKQ==