The Phison PS2251-07 (PS2307) Firmware page on USBDev is the best source. It offers a variety of BIN and FW files, along with MPALL tools suitable for flashing them.
When these drives experience physical degradation, improper disconnection, or a corrupted file allocation table, the micro-controller isolates itself. It enters a protected state, rendering the flash drive completely inaccessible to consumer-level formatting utilities. Software Downloader & Tools Needed phison ps225107ps2307 mptool link