How to upgrade on board ST link of STM32F429ZI discovery board without using ST-link USB debugger

[Vkuma.4]

During testing, Suddenly HOST PC stop detecting the board saying unknown device. NO VID/PID was recorded also. So, we need to upgrade the firmware again But the ST-Link USB is not working only. Is there any other way to upgrade it. Kindly suggest

[Uwe Bonnes]

Replug the device. This should bring up the bootloader. If not, you have trashed the stlink somehow. If the bootloder comes up, download stswlink-0007 and run "java -jar STLinkUpgrade.jar" in the appropriate directory.