For someone with good SMD soldering skill (and a reflow station), changing the MCU shouldn’t be that hard. It’s worth the effort, a MCU costs like 10€.
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Chip replacement went well, it’s happily updating and talking to the VESC tool, but I’ve got a new issue: phase A isn’t working. The motor exhibits the usual stuttering and jittery behaviour when one phase is missing. When phases B or C are disconnected it only buzzes and doesn’t move, when A is disconnected there is not change in behaviour. I’m going to swap 2 the AD8418s to see if it’s one of those that died, is there anything else I should look into?
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It may sound silly but just check there isn’t a loose bullet connector or wire
Measure output voltage of the current amplifiers before you try replacing. Should read 1.65v with no current through the motor.
I’ve blown them with vcc transients and had them stuck at odd voltages.
Unfortunately not, I checked thoroughly, and tested with a multimeter, thanks though 
Ahh, okay, I’ll test now. Thanks! 
Edit: I swapped the chips last night (I didn’t read your post till this morning), and when I plugged it in just now my phase C current amplifier gave out the magic smoke. When I power the board now, I get blue and green LEDs for a few seconds, then just red blinking, no serial. I’m measuring 0.96V on the remaining two current amplifiers. I think I messed up the orientation of the chip on the C phase.
Okay, so I’ve replaced the blown AD8418, then replaced the dead 3.3V DCDC converter with a large linear regulator, and now I’m back to where I started. It connects to the VESC tool, doesn’t report any errors, but the A phase is dead. I’m going to hook an oscilloscope up to the gates of the FETs next to see if the issue is there 
EDIT: Aaaand, DRV error. Great. I don’t know whether to keep replacing parts, or just buy a new one
Since you already replaced everything else you may as well do the DRV as well. Nothing else preventing it from working right?
I thought these weren’t available any more. Have missed a lot in this thread.
I’ve replaced the DRV8301, still getting the DRV error. It says “GVDD_UV” normally, then “GVDD_OV” when I try to run the motor. I measured AVDD to be 6.5V and GVDD to be 11V, neither changes when I try to run the motor 
Drv error dosdent exactly mean the drv is dead, it’s like a car check engine light, it can be multiple things, for example shorted fets durning detection will give out drv errors
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Best guess its one of the FETs then, measure between gate drain and source between em all and see if one sticks out
All outputs had the same 8K ohm between them, and no FET had any shorts. I replaced both phase A FETs, and cleaned the whole board thoroughly (just in case flux being mildly conductive was the cause of issues), but no luck. I can’t find any components that are unique to phase A that I haven’t replaced now
Do you have access to an oscilloscope to check the gate signals?
I do, I’m going to check today. I’ll look at everything I can think of, but apart from the gates, where else should I focus?
Thanks for you help
Guess check all voltage rails. Check for short between ground and vcc. Look for any empty pads on the pcb. Try resolder that drv. Not sure what else there is
Done, everything as expected.
I’m getting two faults, I don’t understand GVDD_OV, as GVDD never hits the 16v required to trigger that fault, but FETHA_OC results in that phase being disabled by the DRV, so that explains why I wasn’t getting any output.
When set the overcurrent mode to “report only”, duty cycle gets stuck at -95% with no input, and phase A is always high, then oscillates when I use the arrow keys, I’ve attached pictures of the scope on phase A and B to show the difference.
Phase B (normal operation)
Phase A (always high)
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Hello guys I have my vesc master that no longer has the green light on, after having updated to FW 3.57… an idea, on vesc tool the slave connects but impossible to connect to the master neither via the usb nor via the can bus it is no longer recognized… When I try to connect it marks me NOT FIRMWARE READ RESPONSE Thanks
Try flashing a new bootloader and downgrading the FW. I had issues with 3.57 too (motor detection)
Thanks but what is the method to make the boot loader…now I’m in the unknown