What could I be doing wrong that makes known good firmware not boot?

[bobcov]

I’m a newbie when it comes to flashing microprocessors. I am wondering if anyone can deduce what I may be doing wrong given the following set of facts.
1. The device I was trying to repair had the symptom of halting after the progress bar instead of booting into its multi-meter software on power-up. This is a well-known fault for this particular meter and there was a set of instructions for saving the calibration from the existing firmware, merging it with a known good firmware and then reflashing.
2. After flashing, I no longer get the progress bar on power up. I get random pixels and nothing more, even though the STM32 ST Link Utility verifies the firmware flashed matches the firmware file. This is also the case if I flash the entire known good file with its included calibration section instead of my saved calibration data. It’s a128K file, the flash starts at 0x08000000.
3. Given that STM32 ST Link Utility says what is flashed matches the source file, what else could I have done wrong that would prevent the firmware from running? nRST_STOP and STDBY and WDG_SW are checked in option bytes. After flashing, I remove the pin holding BOOT0 high. STM32 ST Link Utility sees the processor as STM32F10xx medium density with device ID 0x410. It’s a GigaDevices GDF103xx. I just get the feeling that I am not loading this firmware properly. Very much stumped. Any ideas?

[BarryWhit]

@bobcov, I think your friend is doing you a favor by preventing you from further damage (assuming this "friend" isn't gauging you on the repair and parts). With that said, you can buy these chips cheaply on Aliexpress or LCSC. Replacing them is not hard if you have prior experience and basic tools. But you shouldn't practice on a board you care about.

 

If in-circuit programming facilities are not designed into the board to begin with, it's much safer in many cases to  simply remove the chip from the board for reprogramming, and then remount it.