Where is the charging port on the Billboard BB2442 speaker and what type of cable is needed?
Based on the manual for the Billboard PA speaker series, the "very small hole" you are referring to is likely the Micro USB charging…
Manuals+ Q&A
Billboard PA Bluetooth Speaker BB2530 User Manual — questions & answers
Read product questions and troubleshooting answers linked to Billboard PA Bluetooth Speaker BB2530 User Manual.