First, check these 3 key points:
1. Verify if OTG functionality is enabled on your phone (search for “OTG” in Settings to activate). Note that some older models may not support OTG.
2. Inspect the custom USB drive’s interface (e.g., Type-C/Micro USB) to ensure compatibility with your phone’s port. Poor contact may result from manufacturing deviations in the interface. Third, test the USB drive on another Android device or computer to determine if it’s a hardware issue. If other devices also fail to recognize it, contact the manufacturer’s customer service.

This is primarily due to file system incompatibility or file format issues. Android natively supports FAT32 and exFAT formats. If the USB drive is formatted as NTFS by default, garbled text may occur. Additionally, if the files on the USB drive are computer-specific formats (like .dwg engineering files), the phone won’t be able to read them without the corresponding software. Solution: Format the USB drive as exFAT on your computer, or install an app on your phone that supports the specific file format (e.g., WPS, CAD viewer).

It’s most likely a permission issue or the USB drive is write-protected. First, in your phone’s file manager, long-press the USB drive icon to check if there’s a “Permissions Settings” option. Ensure “Read/Write Permissions” are granted. If write protection was enabled by default during customization to safeguard data (common for enterprise-customized USB drives), contact the customization provider to obtain the method for disabling write protection (such as a dedicated tool or password). Avoid formatting it yourself to prevent data loss.

This is usually caused by unstable contact.
First, check if the USB drive port has dust or oxidation. Clean it with a cotton swab dipped in alcohol.
Second, see if the custom USB drive’s casing is too thick. If it’s squeezed by the phone’s casing after insertion, causing the port to loosen, try slightly adjusting the angle when inserting the USB drive.
Third, replace the OTG adapter cable (if using a Micro USB to Type-C custom USB drive) to rule out cable contact issues. If disconnections persist, it may indicate a hardware fault in either the USB drive’s port or the phone’s port, requiring separate inspection.