Kindly make sure board is kept in flash mode and USB-A to Micro-B cable connected between Host PC and OTG port of i.MX8M Mini. Please refer Hardware User Guide for connection details.
Refer Quick Start Guide (QSG) from below link for connection details,
Get started with i.MX 8M Mini or i.MX 8M Nano Single Board Computer - iWave Systems
For further product inquiries, please get in touch with our sales team at mktg@iwave-global.com
Please find the detailed product information here:
i.MX 8M Mini or i.MX 8M Nano Pico ITX Single Board Computer