YOU SAID:

my hot pocket is not hot but cold.

INTO JAPANESE

私のホットポケットは暑くないが寒い。

BACK INTO ENGLISH

My hot pocket is not hot, but it is cold.

INTO JAPANESE

私のホットポケットは熱くないですが、寒いです。

BACK INTO ENGLISH

My hot pocket is not hot, but it is cold.