J10A JPA0 should be connected to ground

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if j10A is not connected to ground, then its a bit floating, and the sequencer often boots up into bootloader (i do had thad that on a LoopA too!)
so A. Install a bootloader switch on the back off sequencer, which is connected to 3.3V, Gnd, and J10A-JPA0 as middle man…
B. Connect J10A-JP0 to ground > solder a cable for example to AIN A-3-Gnd-Pins….

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Are J10A ports initialised on boot? I don’t think they are. But maybe a modified IDC socket would be another way to do it?

If you install R101/R102, PA0 is pulled down to 0V and should not be floating. If you prefer, the value of R101 could be adjusted. 220k is quite large but that is based off the DISCO board I think.