When a sentence begins in the middle of a quotation, capitalize the first word.
“. . . the platypus is a strange animal,” said the zoologist.
“The platypus is a strange animal,” said the zoologist.
When a name such as a brand or a scientific term starts with a lower case letter, do not use the name to start a sentence.
iPhones are very popular.
The iPhone is a popular brand.
If a number starts a sentence, spell it out. Otherwise, rewrite the sentence without the number as the first word.
23 students enrolled in the class.
Twenty-three students enrolled in the class.
The class had an enrollment of 23 students.