Ensure the filename is exactly what the bootloader expects.
Communities like Drive2 or technical forums often host user-verified binaries for specific board versions like the p50358v30.
Always keep a backup of your original firmware (if possible) before attempting to flash a new version for "Extra Quality" improvements. Firmware Update Bundle (v8.3.0.3) - Lenovo Storage V5030
Because these boards are often manufactured by third-party suppliers, you won't always find them on a standard consumer electronics website. Here are the most reliable methods:
Reconnect the power. On most boards, the indicator light will begin to flash rapidly, indicating the update is in progress.