Pixhawk Firmware Upgrade Failure

After attempting to re-flash my Pixhawk 2.4.8, it wont start up properly as it used to (no startup main LED lighting nor Beeping). Despite that COMM is identified in device manager, QGC is now very inconsistent while syncing with board during firmware setup (Tried multiple USB connections, no success).

After multiple attempts, QGC sometimes syncs and prompts me to choose a firmware. However, I get a flash error while QGC is programming the newer version and so upgrade is canceled [Error: Flash failed: Command failed: 0x11(PROTO_FAILED) at address 0x000fc000]

I have read many forms suggesting a bootloader corruption or a bricked flight controller, any suggestions?