Cannot flash ESC with BLHelii S, letter u is assigned to it

[Deltav]

Hello everyone, I recently got my first mamba stack, tried to flash C-H 40 Multi on my MAMBA F50_BLS using BLHelii S to change motor direction and the second ESC has the letter u assigned to it. Any idea how to fix this? If it is bricked, does anyone know how to unbrick my 4 in 1 ESC and how to find GND, C2D and C2CK on this specific board? Thanks in advance!

 

[koklimabc]

There is it How to Unbrick ESC - Flash BLHeli_S Firmware through C2 Interface - Oscar Liang. If soldering may be is hard you then you could tried to use Jumper wires with hot glued on both end to help you fixed while holding in one hand.

Normally 4 in 1 ESC existed with 4 pair of two tiny solder sport on its back.

 

[Deltav]

For anyone who may face the same problem: Flash using BLHeli configurator as described on this video: