is dead (black screen, no power) after a firmware flash, it likely suffered a due to a mismatched file or interrupted process . Common Recovery Steps
During flashing, the most dangerous step is overwriting the preloader. If the power cuts out, the USB cable disconnects, or the software crashes while writing to this partition, the phone loses its ability to initialize the RAM or boot ROM. Without a preloader, the phone cannot even enter emergency download mode (EDL), effectively becoming a paperweight.