ESP32-S3 randomly freeze in bootloader with an invalid header error message

[Jacques_ESCARGO]

Hi,

Thank you for sharing your answer.

Our issue seems different, we didn't see the "waiting for download" uart log.
Wiring a pullup resistor to GPIO-0 did not solve our problem.

However, we got other boards with a similar design. None of the 6 new boards freezes on startup.

[ESP_Sprite]

GPIO0 has an internal pullup, but it's pretty high in value (50K or something). Could be that some crud on your PCB (e.g. hygroscopic flux that has attracted water) made a, possibly high-resistance, ground path that is nevertheless enough to pull GPIO0 down my just enough.

[Jacques_ESCARGO]

Back then, we tested with a additionnal pullup (something like 10k or 20k Ohm)
Today, we tried with a 200 Ohm pullup resistor on GPIO-0. Unfortunatly, it still freezes.